The Many Mysteries of Darwin IV - Part 2

For part one go here

After a long absence I am finally back to deliver part 2 of this series. In the meantime the reprint of Expedition, the occasion which has inspired these posts, has finally come out and you should definitely check it out if you have not already. After the last part, in which we have examined the orbital mechanics and physical properties of the planet and its parent stars, we will now take a look at the atmosphere and geology of the planet Darwin IV.

My copy of the reprint has finally arrived!

Little is said about the air of the planet in detail, other than that it is denser than Earth’s and that it is very rich in oxygen, both of these characteristics being the main reasons why Darwin IV is capable of hosting not only very large, but also floating organisms. The book however gives us pretty much no figures or hard numbers, such as exact atmospheric mass or composition. The best I could find is again that DVD-brochure for the documentary, which I showed in part 1. It says that the atmosphere has twice the density of that on Earth. If we take this at face value, we may calculate some interesting things. The density of Earth’s air at sea level and at 15 degrees Celsius is 1.255 kg/m³. If we take twice the amount of that, 2.45 kg/m³, and multiply it by the universal gas constant and by 288.15 Kelvin (15 degrees C), the air pressure at Darwin IV’s sea level (whatever that might be since the planet has no oceans) would have a value of about 202’654 Pascal. Note however that this assumes dry air, the calculation for humid air would be more complicated and require data we do not have, though there are a lot of signs that the air on Darwin IV is indeed very dry compared to Earth. I also assumed that Darwin IV has on average temperatures like modern Earth, though we do not get much information on that other than that the climate is “temperate” (Barlowe 1990, p. 17). The air-pressure we calculated equates to 2 atmospheric units or 2.07 bar at sea level. This may at first not sound like a lot, but on Earth this would be the pressure you would feel if you were to dive to a depth of 10.3 meters underwater, twice the depth of your average pool. While this is a joke compared to what one would experience on Venus, roaming the surface of Darwin IV might nonetheless feel more akin to swimming or wading than walking. This, together with the low gravity, certainly does give credence to the sizes and locomotion of the aliens. But again, all of this is based off a DVD brochure, so take these values with a grain of salt.

While Darwin IV has a denser atmosphere than Earth, its surface area is more similar to that of Mars, so calculating the total mass of the atmosphere was a bit tricky. What I did is open Universe Sandbox 2 and create a mock-Darwin IV in the program with all the geophysical properties discussed in part 1. I raised this planet’s air-pressure up to 2 atm and this resulted in an atmospheric mass about 90% that of Earth’s. That is quite a lot for such a small planet, something you should keep in mind. What this atmosphere is made out of is another question. Again, the book is unclear on this, other than that there is a high concentration of oxygen. The documentary barely goes into more depth, but for a few seconds it shows us this graph, which I photographed below from my TV screen:

Unfortunately, the axes are not labelled, so I am unsure what is actually being depicted here. Perhaps the Y-axis is meant to be the height above ground in kilometers, but what is the X-axis then? It is not even said if this is actually meant to be a graph they made up for Darwin IV or if this just some stock image. If you can make more sense of this than I do, please tell me. Without definite values to deduce from this, we have to guesstimate the atmospheric composition by observation. Given how life on the planet’s surface seems to be working off biochemistry not unlike our own, the overall composition cannot be too different from Earth. The majority is therefore likely made up of nitrogen, the rest of oxygen and then a small amount of trace and greenhouse gases. One of the perhaps oddest things we can observe about the climate of Darwin IV is that it rarely rains. This is emphasized in the documentary, where it is addressed that the probes never encounter rain on their entire journey. It does rain once in the book (Barlowe 1990, p. 110), but above the Amoebic Sea, which is (presumably) the lowest area on the planet and is the largest biological structure that would transpire water to the atmosphere. If we also look at the skies of Barlowe’s paintings, we can see that most structures that look like clouds are actually swarms of aerial plankton. We can therefore conclude that the air on Darwin IV holds very little water vapor, which has implications for its atmospheric evolution and its greenhouse effect. This is corroborated by the fact that most of the flora is of the succulent type (Barlowe 1990, p. 15). If this dryness really is the case, it does however raise the question of where all the aeroplankton and floating aliens get their water to live from. Perhaps the air does have decent amounts of water, but like the water on the ground, it is locked up in the aerial biosphere itself, meaning the majority of the water is encased in all the aeroplankton and other organisms and simply gets recycled through the food-chain. However, on one of the title pages (Barlowe 1990, p. 5) we also see some typical large fliers simply landing next to a waterhole and drinking from it, so perhaps many of the other aerial creatures, even if they do not appear to have landing-organs, do have the ability to simply ground themselves and lap up some water from local oases.

The Geology and Geography of Darwin IV

 

Fig 3: The map of Darwin IV I pieced together with my lousy scanner. The black bar indicates where features got distorted by the spine.

The most obvious thing about the surface of the planet is that there are no oceans, save perhaps for the Amoebic Sea, which one might argue cannot even be called a sea. It is however heavily implied for this to not always have been the case, with the current savannahs likely once having been seabeds. The current surface of the planet seems to be relatively young, as Darwin IV has few craters on its surface. This is a sign that the planet is still geologically active, as the surface gets continually renewed through erosion and endogenic processes, like on Earth or Venus. Objects with very little geologic activity, such as Mars, Mercury or the Moon, tend to be plastered in craters they have amassed over the eons and never got rid of. One of the most conspicuous features that rarely gets talked about (perhaps because it was not prominently featured in the documentary) is the large mountain chain which is centered around the equator. I find this very weird, but unfortunately this placement is never elaborated upon. How did it come into that position? One of the first things Darwin IV’s mountains reminds me of is the real-life moon Iapetus. The third-largest moon of Saturn has a somewhat similar mountain chain (or really ridge), which rises 13 km above the surface and almost perfectly girdles the moon’s equator. Unfortunately, the reason for this ridge’s existence remains controversial. One hypothesis is that the ice moon used to rotate faster and was more plastic in its past and as it slowed and cooled down, the ice-sludge that centrifugal forces brought to the equator began to freeze in place. Since Iapetus is an ice moon and Darwin IV is a rocky planet we can obviously not use this as an analogy however. Another hypothesis is that Iapetus’ ridge is an actual mountain chain created by convective forces under the surface and that these pushed towards the equator due to coriolis forces. This might be more applicable to Darwin IV. The text does at least insinuate something to that extend:

“The mountains of Darwin IV are relatively young, sharp-edged and jagged, though not terribly high. Very few peaks remain sheathed in snow through the year. Looking all the more forbidding for their bareness, they form a planet-girdling band, evidence of Darwin IV’s active sub-continental shield regions.” (Barlowe 1990, p. 129).

On that note it is interesting to ask whether or not Darwin IV has plate tectonics like we know them and if these “sub-continental shield regions” are actual tectonic plates. As mentioned in part 1, the internal structure of the planet is, based off its density, likely considerably different from Earth’s. Looking at the map of Darwin IV it is also hard to recognize any features one would expect from plate tectonics, especially if you compare it with maps of Earth where the oceans are digitally removed. There is a large valley on Sinus Columbus, which seems to be splitting the mountain chain in half, however that is not how a typical diverging plate boundary would look, as those usually form volcanic ridges in their midline, the Mid-Atlantic Ridge being the most prominent example. Perhaps it is just the dried-up bed of an ancient river. One can see other ridges and rifts, but these are curiously arranged perpendicular to or bisecting the mountain chain. I we assumed that the mountains formed through plate-collisions, these features should instead be arranged in parallel to the mountain chains.

Fig. 4: Image of equatorial ridge of Saturn’s moon Iapetus, taken by the Cassini space probe.

Perhaps more similar to Darwin IV’s mountains than the Iapetus Ridge are instead the highland regions of Venus, such as Ishtar Terra or Aphrodite Terra. While Venus does show signs of obvious tectonic deformation on its surface, it is a debated question whether or not it actually has plate tectonics like Earth, as, like Darwin IV, it has no obvious signs of spreading ridges or subduction zones. It is thought by some that Venus has no real asthenosphere and that its surface tectonics are caused by direct mantle upwellings which can either compress, spread thin or delaminate the overlying crust from underneath. Another, though related hypothesis is that Venus does have a form of plate tectonics, but that its plates are all micro-sized and paper-thin and/or that all the action that happens is buried underground, with the topmost surface layer being too buoyant and stiff, due to its dryness and heat, to move with the plates underneath, therefore getting deformed in weird ways through delamination. This does sound a lot like the “sub-continental shield regions” Barlowe writes about. Like Venus, Darwin IV may currently not have Earth-like plate tectonics due to the lack of water on its surface. On Earth the abundant presence of water in the crust not only “lubricates” the movement of the plates, but also creates different densities when new crust is formed. These density-differences are what allows oceanic crust to be subducted by continental crust in the first place. Applying similar models and what we learned from Iapetus to Darwin IV, we might speculate that centrifugal forces create either an upwelling or downwelling region under the equator of the planet, which causes convective currents to delaminate the crust at the polar regions and compress and pile up material at the equator. Local hot spots then may also compress and spread out the other plains, valley and rift regions we see, such as Sinus Columbus.

Fig. 5: Topographic map of Aphrodite Terra on Venus. There is something oddly scorpion-like about it.

Applying Venusian geology to Darwin IV may however be problematic. The global conveyor belt of Earth’s tectonic plates allows for the heat caused by radioactive decay in the planet’s interior to escape safely and gradually. On Venus however, the heat just keeps building up underneath the crust, to the point where it cannot be stored anymore and violently erupts in what is called a global resurfacing event. The last time this happened on Venus was 800 to 200 million years ago and it is thought that during this event the majority of the planet’s surface was covered by streams of lava as deep as 5 to 10 kilometers (Grinspoon 1997, p. 262). Could Darwin IV have suffered from a similar episode? The land surrounding the mountain chain does look suspiciously smooth, but that may be explained through a whole lot of other reasons. More importantly, it is highly doubtful if any higher lifeform on the planet would have been capable of surviving such an event (unless maybe all the terrestrial organisms we see descend from air-dwellers). If Darwin IV ever had such a resurfacing event, it must have been in the very distant past, long before complex life evolved and the oceans vanished. More likely than that, it never experienced a resurfacing episode, for the simple fact that it is much smaller than Venus. Darwin IV has only about 16% the mass of Earth and a volume and surface size similar to Mars. That means it has a lot less radioactive material that can heat the core and a higher surface area compared to its volume from which heat can escape. In other words, the planet most likely is never able to produce enough internal heat for a resurfacing event to take place or cooled down before the threshold for such an event was reached. This in turn does however raise the question of how Darwin IV is still geologically very active and has not cooled down to the same degree as Mars has. Keep this in mind too.

Lastly one might ask whether or not Darwin IV has a magnetosphere. The strong magnetosphere of the Earth is caused through an inner dynamo, produced by temperature differences and rotation in the liquid outer layer of the core. As established in part 1, the closest analogy for Darwin IV’s interior structure might be Mercury, which does have a magnetosphere caused by such a dynamo, though only 1.1% the strength of Earth’s. Venus, which may match Darwin IV in geophysics as well, has a negligible magnetosphere produced by the ionosphere’s interaction with solar wind, not by an internal dynamo. The cause of this is thought to be the internal build-up of heat, which shuts down most convective currents at the core. Mars, which is similar in size to Darwin IV, has currently no real magnetosphere to speak of. For all these reasons it seems likely that Darwin IV has at best only a very weak magnetosphere. “Wouldn’t then everything on the surface die from radiation?”, you may ask, to which I would answer: Probably not. The idea that it is the magnetosphere which primarily protects us from cosmic radiation is common, but far from being a fact. As James Kasting points out in his critique of the Rare Earth hypothesis, a sufficiently thick atmosphere is already enough to do that job (Kasting 2001). Our own magnetosphere significantly weakens or may even disappear entirely during geomagnetic reversals, which happen on average every 450’000 years, yet there is no real evidence that these events have ever caused mass extinctions, likely for the aforementioned reason. With an atmosphere of nearly the same mass but twice the density of Earth’s, life on Darwin IV is likely sufficiently protected from cosmic radiation. Nonetheless, the lack of a strong magnetosphere does still have important implications for the atmospheric evolution of the planet.

Piecing together the Past

Not much is said or known about the planet’s past, except for the expedition’s speculation that the grasslands perhaps once used to be sea-floor (with emphasis on speculation), this bit of information:

“Evidence in the form of countless fossilized tree stumps scattered throughout the plains has led our chief botanist, Dr. Dorothea Kay, to postulate that Darwin IV was once a far warmer and more humid planet.” (Barlowe 1990, p. 12).

And this speculation on why almost all of the animal life relies on sonar and lacks camera-eyes:

“It is the expedition’s best guess that animals who had developed these sensory organs proved too formidable for those creatures with rudimentary optical abilities struggling for life and dominance in Darwin IV’s thick, primordial mists. Now the mists are gone, but so are the optically sighted animals.”

We can therefore assume that Darwin IV was not only warmer and wetter in its past, but also used to have a fairly opaque atmosphere. This is somewhat reminiscent of theories about Mars’ early atmosphere. Due to the faintness of the young sun, it is thought that early Mars must have been warmed not only by a strong cocktail of greenhouse gases but also by layers of CO₂ ice-clouds. As Forget and Costard describe:

“We can envisage a dense atmosphere, rich in CO₂, with a tendency to condense into clouds of CO₂ ice. These clouds would have been able to reflect and effectively trap thermal radiation emitted from the surface, thereby considerably warming the atmosphere. We might therefore picture a youthful Mars swathed in dense clouds, below which rivers flowed in perpetual semi-darkness.” (Costard 2006, p. 70).

Applying similar conditions to Darwin IV would explain why all the animals seem to descend from ancestors adapted to low light conditions. However, drawing parallels between the atmosphere of Mars and Darwin IV may not neatly work out. Like discussed in part 1, Darwin IV is likely placed more favourably in its star’s habitable zone than Mars, making such atmospheric chemistry unnecessary. Unlike Mars, the alien planet also still has a very dense atmosphere and hospitable temperatures and humidity on its surface. This is likely because Darwin IV has a way higher gravity than Mars (60% that of Earth’s in fact) and was therefore better able to retain its air. A Mars-like model for Darwin IV would therefore not sufficiently explain where its water went and also not why this dark ice-cloud climate stopped at some point. Photosynthetic life would also likely not develop well under such darkened conditions. Perhaps the mists Barlowe writes about are meant to be taken literally and the air used to be filled with tons of water vapor. This might actually make more sense based on what we learned so far and could also explain where all the water went afterwards. Due to the known processes of planetary formation, Venus is thought to once have had large bodies of water, perhaps even oceans, on its surface. Due to its proximity to the sun a lot of that water became vapor in the atmosphere, creating a strong greenhouse effect, as water vapor is a powerful greenhouse gas even stronger than CO₂ and methane. The planet heated up to a point where more and more of the water evaporated. This in turn stopped the subduction processes of any of the tectonic plates that may have been present on Venus. Surface crust became saturated with carbon without being recycled, causing CO₂ to amass in the atmosphere, worsening the greenhouse effect until all the seas evaporated, creating the runaway greenhouse effect that is responsible for the hellish conditions we see on the planet’s surface today. Even if Darwin IV is not as close to its parent stars as Venus is, we might apply a similar process to the alien planet if we consider the possibility that it was not all that wet to begin with. Based on the map, it does not seem like the majority of the surface was covered by continuously connected oceans, like on Earth, but rather by singular large seas/lakes of similar size to the Amoebic Sea (similar conditions are in fact speculated for primordial Venus). While that would be considerably wetter than the current Darwin IV, it would have made the crust still too dry for subduction to take place, halting carbon recycling, increasing the atmospheric mass through volcanic outgassing and starting a runaway greenhouse effect that evaporated much of the surface water. The planet would have then been dominated by a warm, humid, but also misty hothouse climate exactly as described. Now of course, the first objection one might raise to this scenario is that Darwin IV cooled down again after this happened, while Venus went on to become an infernal hellscape. The reason for this might again be the difference in mass and gravity. Darwin IV and Venus both have wimpy magnetospheres, causing molecules in the upper atmosphere to be easily disintegrated into their components by radiation, but the alien planet additionally also has a lot lower gravity, making it easier for gases to escape the atmosphere. Not to mention that Darwin IV orbits an F-type star, which have a stronger energy output than our own sun and would therefore erode planetary atmospheres even stronger through solar wind. All these factors would help counteract the extreme conditions of a Venus-like greenhouse effect, while at the same time literally bleeding the planet dry. The water in the atmosphere may have been split up by radiation into oxygen and hydrogen, with the hydrogen being carried off to space by solar wind, at about the same rate that it evaporated from the surface. The majority of Darwin IV’s currently high oxygen content may have been produced this way, as, apart from the aeroplankton, the vegetation does not seem extensive enough to account for it. The same process of atmospheric loss may have also happened with the CO₂, if it were not already being kept in check by photosynthetic life on the planet. At some point the atmosphere would have simply run out of enough vapor to keep up its greenhouse climate, with what was left being locked up in the biosphere. With most of its surface water and forests gone, the surface now also began reflecting more radiation than it was previously absorbing, increasing albedo and cooling down the planet. Simultaneously the planet’s interior may have significantly cooled down, slowing geologic activity and in turn volcanic outgassing. In time the planet cooled down enough that most of the water that was left became concentrated into polar ice caps, increasing the albedo even further. The planet now went from a humid hothouse to an arid ice age climate. The aliens found themselves now in a world without primordial mists but also without much rain or forests. 

Fig. 6: Even the highest mountain-peaks on Darwin IV often lack snow, a strong sign of lacking humidity in the air.

The last major question one might ask here is how old the planet is and when approximately these events may have taken place. Since the world seems to already be past its prime one would assume that it is already quite old by our standards. The age of the planet is unfortunately given neither in the book nor the documentary. The only hard number we ever get is again from the DVD brochure, which states the planet is 2 billion years old. For us humans, who live on a 4.56-billion-year-old planet, this does seem surprisingly young. Should we therefore simply dismiss this as non-canon? Do not forget that Darwin IV orbits an F-type main sequence star. Our own sun, a G-type star, may have a total lifespan of about 10 billion years, with the Earth becoming uninhabitable long before that however. By comparison, F-type stars remain stable for only 2 to 4 billion years (“a candle that burns twice as bright burns half as long”). Assuming the latter end-date for Darwin A, Darwin IV being only around 2 billion years old places its age in the middle of its sun’s lifespan, just like Earth, making this actually a quite plausible age. It would also explain how the planet is still geologically active despite its Mars-like size, as it simply has not run out of energy yet. Obviously, you may object to this by saying that the life we see on Darwin IV is way too advanced for such a young planet. The planet is arguably in its “dinosaur-stage” of development, something stated by the author himself, or even its stone age if you take the Eosapiens into account. On Earth nearly the first 4 billion years were dominated by unicellular life, with multicellular organisms only taking over in the last 500 to 600 million years and the first terrestrial megafauna arguably appearing with the Late Permian therapsids 260 million years ago. But who is to say that the long tyranny of microbes will be a universal constant on other planets as well? Consider for example the Francevillian biota, a group of fossil organisms I talked about before. These fossils from Gabon appear to be multicellular, eukaryotic organisms which lived 2.1 billion years ago, or in other words when the Earth was just 2.4 billion years old. The oldest geochemical evidence for eukaryotic cells in the form of steranes is 2.7 billion years old (Knoll 2003, p. 94), meaning these organisms evolved “just” 600 million years after the first complex cells showed up. More astounding is the find of a multicellular algae fossil from the Russian Kola Peninsula, which was found in rocks dating to 2.45 billion years ago (Rozanov et al. 2013). This halves the gap between the oldest known eukaryotes and the appearance of multicellular organisms to 300 million years. Unlike these algae, the Francevillian biota seems to have gone extinct shortly after it evolved due to a global anoxic event. If that had not happened, there is nothing that says that these organisms could not have diversified further and begun their own version of the Cambrian radiation, all the way back in the Paleoproterozoic era. Findings like these show that complex life may have had the chance to develop all throughout the Precambrian eons, but simply got unlucky. This perhaps shows that Earth may actually be less hospitable to complex life than other planets. The appearance of eukaryote-type cells themselves is generally thought to be an endosymbiotic chance event and may happen at random times on different planets. On Earth they appeared around 1.8 billion years after the planet’s formation, on Darwin IV (which like Mars may have cooled down and become habitable quicker than Earth), they could have appeared just 1 billion years after its formation. Assuming an optimistic scenario we gleaned from our own fossil record, first multicellular life could have then appeared just 300 – 600 million years afterwards and if it were lucky enough to not get completely wiped out it would have had an additional 400 - 700 million years to evolve and diversify into the forms we now see on Darwin IV. That is of course assuming that cellular life on the alien planet works by the same prokaryotic-eukaryotic divide as ours, but it may very well not. Perhaps biochemistry on Darwin IV was weird enough that even the oldest cell-types had sufficient pre-adaptations for evolving multicellularity, making the time of appearance of eukaryote-type cells a moot point. One might also consider Darwin IV’s weak magnetosphere. While not enough to cause mass extinction, the biosphere on average might still receive more radiation than it does on Earth. This would heighten the mutation rate of the lifeforms, which in turn would accelerate the rate of evolution, further shortening the time between major evolutionary events. But for simplicity’s sake let us work with the aforementioned scenario. Assuming that the mass-diversification of multicellular organisms corresponds with oxygenation events, this rough timeline may help us constrict the times of atmospheric evolution. Like mentioned before, most of the oxygen in Darwin IV’s atmosphere may not come from drawn out photosynthetic processes, like it did on Earth, but instead from the splitting of water vapor in the upper atmosphere during its phase of intense greenhouse climate. The first appearance of multicellular life may therefore very well correspond with the beginning of this intense greenhouse climate. As this was shortly followed by the evaporation of most seas, it would have forced the first animals and plants to quickly adapt to life on the misty land (which is not problematic, seeing as how some of the oldest terrestrial trace fossils on Earth date as far back as the Cambrian). When exactly the change from hothouse to coldhouse climate happened is hard to say, though the hothouse climate seems to have persisted some considerable time after the seas had already evaporated, seeing how there are fossilized forests at the bottom of former seabeds. The vanishing of the mists also seems like it could not have been that long ago, as all the animals, except for the Rimerunner, work with sensory organs still adapted to that environment.

Based on everything we have discussed I have made this very basic timeline:

Now that we have most of the basics down, in the next part we can finally analyze the life on Darwin IV in more detail. Thank you for reading and see you until then.

If you liked this and other articles, please consider supporting me on Patreon. I am thankful for any amount, even if it is just 1$, as it will help me at dedicating more time to this blog and related projects. Patrons also gain early access to the draft-versions of these posts.

Related Posts:

• The Many Mysteries of Darwin IV - Part 1
• The Alien Prehistoric World Trope: Part 6 - Just Plain Barlowe
• Solved and Unsolved Fossil Enigmas - Part 1

Literary Sources:

• Barlowe, Wayne: Expedition. Being an account inword and artwork of the 2358 A.D. voyage to Darwin IV, New York 1990.
• Barlowe, Wayne: The Alien Life of Wayne Barlowe, Beverly Hills 1995.
• Cohen, Jack/Stewart, Ian: Evolving the Alien. The Science of Extraterrestrial Life, London 2002.
• Costard, François/Forget, François/Lognonné, Philippe : Planet Mars. Story of Another World, Paris 2006.
• Grinspoon, David Harry: Venus Revealed. A New Lookbelow the Clouds of our Mysterious Twin Planet, Cambridge 1997.
• Knoll, Andrew: Life on a Young Planet. The First Three Billion Years of Evolution on Earth, New Jersey 2003 (Second Paperback Edition).

Papers:

• Kasting, James: Peter Ward and Donald Brownlee’s “Rare Earth”, in: Perspectives in Biology and Medicine, 44, 2001, p. 117 – 131.
• Rozanov et al.: A unique find of the earliest multicellular algae in the Lower Proterozoic (2.45 Ga) of the Kola Peninsula, in: Doklady Biological Sciences, 449, 2013, p. 96 - 98.
• Sato et al.: Habitability around F-type stars, in: International Journal of Astrobiology, 13, 2014, p. 244 – 258.

Image Sources:

• Fig. 3: Barlowe 1990, p. 2 – 3.
• Fig. 4.: Wikimedia
• Fig. 5: Wikimedia
• Fig. 6: Barlowe 1990, p. 118.

Antique Paleoart: Dragons of the Air

Pterosaurs definitely do not get enough love, even these days. Of course, everyone knows who they are and there is rarely any dinosaur-media that leaves them out, but they are almost never the focus and are rather treated as an “Oh yeah, these existed too” or are even just there to add scenery. Once every blue moon, however, when the stars align and the magi sacrifice a virgin on Mount Ararat, it is decided that the pitiful reptiles will be granted a book of their own. The first instance of this happening comes to us from 1901 with Dragons of the Air: An Account of Extinct Flying Reptiles. This was written by none other than British paleontologist Harry Govier Seeley, who is maybe primarily known for being the one who split Dinosauria into the groups Saurischia and Ornithischia based on the shape of their pelvic bones. The book is rather technical and mainly filled with skeletal drawings and anatomical comparisons, but the few life-restorations in it reveal a remarkably prescient view for the time.

While Seeley does definitely classify pterosaurs as reptiles (and not as marsupials or weird bat-bird-hybrids as some have done before him), he nonetheless believed that they are the closest relatives of birds, renaming them Ornithosauria. Thus he reconstructed them with a similar physiology. This is rather remarkable, considering what other paleontologists at the time thought of them and how they would be stereotyped the following decades. Throughout the twentieth century pterosaurs were reconstructed as cold-blooded reptiles, which on the ground were only capable of awkwardly crawling or even resorting to sluggishly pushing themselves forward with their feet. Meanwhile Seeley here drew Cycnorhamphus suevicus as an upright quadruped, as would only become the standard for pterosaur-reconstructions almost 100 years later (complete with shrink-wrap!). In fact, the only difference between this reconstruction’s posture and that of modern ones is that the feet are digitigrade. Today we know, based off footprints, that they were plantigrade.

Most well-known of Seeley’s illustrations is likely his reconstruction of Dimorphodon, as it was used both in Peter Wellnhofer’s and Mark Witton’s books about flappy bois to show off how prescient he was for his time. Personally, I find the Cycnorhamphus above a bit more impressive, as the Dimorphodon here still looks vaguely bat-like. I assume Wellnhofer and Witton still liked to use Seeley’s Dimorphodon instead, as the quality of the drawing is much higher and more reminiscent of modern reconstructions. Perhaps it was also a way for them to stick it to Kevin Padian who throughout the 80s and 90s reconstructed Dimorphodon as a dinosaur-like biped.

If the latter is the case, Seeley does unfortunately also feature skeletal reconstructions of Dimorphodon in bipedal posture. He considers a bipedal posture for this animal plausible due to the shape of the fingers and claws, which he thinks look decidedly more raptorial than the feet and may have been used in seizing prey, again attesting to his dynamic, active view of these animals. Scaphognathus on the right is also reconstructed in bipedal posture, though notably next to a quadrupedal Rhamphorhynchus. It is probable that he made bipedal reconstructions in addition to the quadrupedal ones to draw a stronger comparison between birds and pterosaurs. While today’s consensus is that pterosaurs were quadrupeds, there still are some minority opinions, based off possible footprints, that some of them were bipedal. A 2020 study on such footprints from Korea has however revealed that most if not all of these supposed bipedal pterosaur-tracks were actually made by bipedal crocodylomorphs instead.

As we look at his Cycnorhamphus fraasii (which I believe would today be called Pterodactylus/Diopecephalus kochi) the most notable difference between this and modern reconstructions that comes to mind is of course the lack of pycnofibers, which we nowadays know pterosaurs definitely had (despite what Brazilian-fossil-poacher David Martill wants to tell you). This has been consensus since the 1970s, though Seeley does notably already discuss the idea of pterosaurs having feathers in this book. The reason is that as early as 1831 Georg August Goldfuss reported seeing filaments on the fossils of Scaphognathus and Germanodactylus. Unfortunately, Seeley and other paleontologists dismissed the idea and interpreted these filaments as wrinkles made by the wing-membrane, perhaps because the idea of fuzzy pterosaurs ran counter to the classification of them as reptiles. Seeley could have really done himself a favour by accepting Goldfuss’ interpretation, as it would have helped him in his major debates with Richard Owen, who viewed pterosaurs as cold-blooded primitives. In 2002 Goldfuss was eventually proven right as a study using UV-photography confirmed that what he saw were indeed fossil filaments.

Now here is a little lesson in science-history. What you are seeing here is a so-called quinarian system. This was a popular classification scheme among British zoologists before the idea of evolutionary family-trees became common. Remember that scene in the Dinosaurs TV show where Earl Sinclair classifies all dinosaur wisdom into the three categories animal, vegetable and rock? This is kinda similar. The base idea is that any one group of organisms can be divided into roughly five, or in this case six, sub-groups (and if you happen to find fewer than five it just means there are groups still waiting to be discovered). Nowadays this may seem highly simplistic, but it made sense at a time when most scientists still ascribed to the Aristotelian idea that most forms in nature are based off metaphysical templates. The diagram on the left is Seeley’s system of a group called Ornithomorpha, which he defines as the groups most adjacent to birds. As mentioned earlier, Ornithosauria (what he calls pterosaurs) he imagines as having developed in parallel to birds and is connected with them through the Saurischia and Aristosuchia (the latter being sort of a waste-basket taxon for the archosaurs he couldn’t shove into the other five groups). This is admittedly not too far off from how we see these relationships nowadays, though in other parts of the book he also classifies pterosaurs as the closest relatives of birds, both sharing a close common ancestor in the Paleozoic, making his views on relationships kind of confusing. For us it gets weirder once we view his larger-scale classification of the tetrapods on the right, with the Ornithomorpha being most closely adjacent to the Sauromorpha (a group he defines as comprising the turtles and tuatara, but also anomodonts, protorosaurs and plesiosaurs) and Mammalia. The latter he justifies through some mammal-like characteristics in the pterosaurs, comparing certain details of their anatomy with the synapsids found at the time in the Karoo Basin.

Lastly I just wanted to show you his small classification guide for the different pterosaur-groups because I think it is cute. Over all this was an interesting book to read through. It is really a shame that it took 90 years for another major book about pterosaurs to be released (The Illustrated Encyclopedia of Pterosaurs by Peter Wellnhofer) and after that one another 22 for Mark Witton’s Pterosaurs. The latter is still a great reference, though it has already aged in some areas through the past seven years. Pterosaur literature really ought to keep up with the current rate at which dinosaur books are published.

If you liked this and other articles, please consider supporting me on Patreon. I am thankful for any amount, even if it is just 1$, as it will help me at dedicating more time to this blog and related projects. Patrons also gain early access to the draft-versions of these posts.

Related Posts:

• Antique Paleoart: Journey to the Center of the Earth
• The weirdest things people have thought about pterosaurs
• Unorthodox Ideas about Bird Origins

Literary Sources

• Martyniuk, Matthew: Beasts of Antiquity. Stem-Birds in the Solnhofen Limestone, Vernon 2014.
• Seeley, Harry Govier: Dragons of the Air. An account of extinct flying reptiles, London 1901.
• Wellnhofer, Peter: The Illustrated Encyclopedia of Pterosaurs. An illustrated natural history ofthe flying reptiles of the Mesozoic Era, New York 1991.
• Witton, Mark: Pterosaurs, New Jersey 2013.

Papers:

• Kim et al.: Trackway evidence for large bipedal crocodylomorphs from the Cretaceous of Korea, in: Scientific Reports, 10, 2020.

Fossil Hunting in the Jura Mountains of Holderbank

 

Another one of my trips through prehistoric Switzerland, this time in the Jurassic sponge-reef of Holderbank, Aargau. I do not have much to add to this video textwise, so instead I will use the quick opportunity here to raise awareness for a far better fossil hunter and paleontologist than I am: Mary Anning. Just yesterday I found out that a new crowdfunding campaign has been started by 11-year old Dorset girl Evie Swire and her family in order to raise money for a statue of Anning to be erected in her hometown of Lyme Regis. As Anning, in my opinion, still often doesn’t get enough credit for some of her work, I highly encourage my readers to at least pay attention to the project.

Click here for the campaign

That is it for now, we will likely see us again around Christmas time.

If you liked this and other articles, please consider supporting me on Patreon. I am thankful for any amount, even just 1$, as it will help me at dedicating more time to this blog and related projects. Patrons also gain early access to the draft-versions of these posts.

Related Posts:

• My Trip to the Dinosaur Museum of Frick

Antique Paleoart: Journey to the Center of the Earth

Because I am nothing but unoriginal I decided to basically rip off Love in the Time of Chasmosaur’s long-running Vintage Dinosaur Art series, though of course with a twist. These definitions are naturally somewhat subjective, but a cultural object is usually defined as “vintage” if it is at least 25 years old (meaning Jurassic Park is already vintage and its first sequel will be as well in two years). Once something is older than 100 years it however stops being vintage and instead becomes an antique, which is where I want to jump in. In this new category I want to take a light-hearted look at paleoart (mostly from books), which is at least 100 years old, which at the point of writing would be anything made before 1920. To kick this off nicely I decided to begin with a true classic: Voyage au centre de la Terre by none other than Ur-sci-fi-author Jules Verne. While it was technically first published in 1864, the definitive and most famous editon was the 1867 reissue, which featured artwork by one Édouard Riou. Riou may perhaps not be such a big name anymore in today’s discussion around paleoart, considering all the Knights, Burians and Pauls that came after him, but he is still indispensable for the history of the medium for illustrating Louis Figuier’s The Earth before the Deluge in 1863 (which I still need to get my hands on). While Figuier’s book still worked off a biblical narrative, it was the first major book aimed at general audiences that told and illustrated Earth’s geologic history through the ages, making it the precursor to basically every popular non-fiction dinosaur/prehistory-book written after it. Without it we might never have had books like Life through the Ages, All about Dinosaurs, Life before Man or All Yesterdays and paleoart might still be relegated to dry scientific papers. It was also exactly this work which most scholars agree was the inspiration behind Verne’s novel.

In the rare case you do not already know the basics of the story, the novel follows the adventure of the clumsy German geology professor Otto Lidenbrock and his nephew Axel, who, together with the stoic Icelandic guide Hans, follow the trails of a long-dead monk down the lava tubes of a long-dead volcano to discover a fantastical biosphere deep under the Earth. The first third of the novel mainly concerns the rather drab travel towards and down the volcano, without any wildlife-encounter, but I still wanted to include this Riou-illustration of a gigantic crystal cavern. The reason is that, while in Verne’s time this was seen as fantastical, real-life caverns like this have been discovered in the form of the Naica Mine in Mexico. Another thing to add to the long list of things Verne predicted, which also includes travelling to the Moon, giant submarines, skyscrapers and even the internet. Take that H. G. Wells!

Technically our first illustration of extinct life comes when the expedition team travels through a naturally hollowed out coal-deposit. While not outright stated in the text, it is quite clear that what is depicted here are petrified Calamites trees. In the Carboniferous these giant horsetails, together with scale-trees, were near ubiquitous in the ancient coal swamps. Fossils like these have even been found near where I live at the Swiss Tödi mountain and the town of Dorénaz. Axel, the narrator and whose opinions basically reflect mainstream geology of the time (as opposed to his uncle who’d be considered an odd crank nowadays), uses this passage to tell us a bit about the Carboniferous and Devonian times and their inhabitants. Interestingly for us today, he muses that through the overconsumption by the industrialized nations the world’s coal-deposits might be completely depleted in about three centuries. From Jules Verne’s POV while writing the novel, that would be in around the 2160s. Since the global industrialization has only expanded since his time I wondered how well this prediction would hold up. At least according to this paper our known coal deposits might last until the 2110s, with all other fossil fuels already running out by the 2040s. I have however also found some sources claiming that coal might already run out by the 2060s, so Verne’s prediction might be 50 – 100 years too optimistic. Of course, none of this would be a problem if we simply stopped using fossil fuels and start relying on renewable resources.

After travelling further down the lava tubes, the expedition finally comes to a titanic, perhaps continent-sized cavern, which houses the Lidenbrock Sea and which is lighted by electric clouds under the cave ceiling. After walking along the sea’s beach they come across a forest of giant mushrooms, a truly iconic image. While this was of course pretty fantastical even in Verne’s time, in hindsight there is something funny about this, seeing how we nowadays know of Prototaxites, a Devonian, pillar-shaped lichen which grew about 8 meters tall and dominated the landscape before actual trees evolved. Prototaxites had been known since 1843, though the suggestion that it was a fungal organism had not been made until 2001. Maybe we can add this to the list of Verne’s predictions too. Inside the mushroom forest they also find Carboniferous trees, living versions of the ones they previously saw in the coal ore. Among these on the ground they find bones of various extinct mega-mammals, like Mastodon, Megatherium and Deinotherium. It is left open whether these are the remains of animals which recently lived in the underground forest or if these are fossils swept here from the above-world by sinkholes or similar geologic forces. As they do not see any living ones, Axel assumes the latter, while Lidenbrock likes to think it is the former.

Shortly after, they build a raft and decide to cross the Lidenbrock sea to explore the other shore. At sea they encounter gigantic algae and catch blind descendants of the Devonian placoderm Pterichthys (today referred to as Pterichthyodes, the animal which I currently use as my profile picture). This first encounter with a genuine prehistoric animal makes Axel daydream about travelling to the past and encountering other extinct lifeforms. This dream is what is depicted in the above image by Riou. The mammal on the bottom left is, I assume, Anoplotherium, the one on the right is not an anteater but the giant sloth Megatherium. Yes, back then it was thought that Megatherium had a trunk like a tapir, as can also be seen with the famous statues at the Crystal Palace Park. In more recent years it has also come into question if giant sloths like these, especially the ones living in areas like Florida or Brazil, really were as shaggy as often depicted instead of being naked like most large mammals. Speaking of fur, the two mastodons at the beach are notably drawn without any. As recently discussed by Mark Witton this may actually be closer to the truth, as the idea of mastodons being as hairy as mammoths is entirely born out of paleoartistic convention rather than actual evidence. Nice job, Riou. The Mesozoic reptiles in the background are of course very much of their time, but still give the piece a nice atmosphere. The marine saurians greatly resemble the same ones from Riou’s previous work on La Terre avant le Deluge and the pterosaurs also remind me of another piece of art, but I cannot quite put my finger on which one. Oh, and look, a moa! That should fill our dinosaur-quota for the day. On its own this is a really nice piece, even if deliberately anachronistic, but what diminishes it is that it is just a dream-sequence. But do not worry, this initial disappointment is just build-up for when the real-deal comes!

After a few days at sea, the expedition tries to fathom the depth of the water by letting down a pickaxe attached to a rope. After they pull it out of the water again they see that the axe has been heavily dented by gigantic, crocodile-like bite-marks, a definite sign that they pissed off something big and scary. The next day they are woken up as a gigantic animal hits their raft. What I really like about this image is the sort of creepy vibe. This could just as well have been an illustration in one of those Bernard Heuvelmanns’ books about sea-serpents or other marine cryptids… which is of course because the modern vision of sea-monsters was based off this era’s science on Mesozoic marine reptiles. In hindsight, books like Journey to the Center of the Earth or Arthur Conan Doyle’s The Lost World probably contributed a lot to the “prehistoric survivor paradigm” which has made cryptozoology the laughingstock that it is nowadays.

After the initial shock they see a multitude of animals in the distance, a whale, a crocodile and a lizard on one side and a giant tortoise and a sea serpent on the other. As they come closer however they see that it is just two creatures whose body-parts they mistook as belonging to separate animals: an ichthyosaur and a plesiosaur. To us this mistake may sound odd, but it emphasizes just how alien these animals were to the people of the mid-nineteenth century. I bet that this was Mary Anning’s first reaction upon discovering Plesiosaurus. What follows this odd encounter is what most people would consider the signature scene of the novel. In fact a colored version of this image is used as my edition’s cover. Now of course we could spend all day talking about how outdated this reconstruction has become, but come on man, scenes like this are what we are all here for. Raw antediluvian brute force! It is interesting to compare this to Riou’s previous illustration of the two animals in Deluge. There they do not fight, but just look mildly annoyed at each other. In Deluge they also are more anatomically accurate and have smooth skin, while here they look more monstrous and are decked out with almost turtle-like armor-scutes. It is probably safe to say that Riou deliberately made the animals more exaggerated here for added entertainment value. Also interesting to note is how this image demonstrates the fact that people at this time thought the sclerotic ring of ichthyosaurs was visible in life, as can also be seen at the Crystal Palace sculptures.

After an odd encounter with a geyser and a kugelblitz, the expedition finally lands on the far side of the shore. There they encounter a giant fossil graveyard, strewn with the bones of various extinct mammals and reptiles. It is again left uncertain if these bones came from animals living underground or sank down here from above.

Among the bones they shockingly find the remains of a prehistoric human. Mind you that this was at a time when the existence of humans in faraway geologic history was still controversial and remains of fossil hominins were still rare. Charles Lyell had just written Geological Evidences of the Antiquity of Man in 1863 and the identity of the neanderthal remains was still called into question by some. What follows is Otto Lidenbrock audibly daydreaming of standing in his lecture hall and making fun of the scholars which doubted the antiquity of man. Though something seems off with this haunting image The skeleton does not look like a fossil, but rather like a mummy as it still has hair and skin.

After crossing the graveyard, Otto and Axel enter a large forest filled with Cenozoic plants. There they find a herd of still living (and naked) mastodons and, dumbfoundingly, a gigantic human leaning against a tree with a large club, apparently tending the mastodon herd like they are its cattle (so Verne maybe also predicted Skyrim?). The sight is so terrifying that the two explorers flee the forest, in fear that the giant might spot and attack them. Axel finds this encounter so unbelievable that he tries to tell himself in retrospect that what they saw just was just a large ape, but we readers know better thanks to Riou’s illustration. The way he drew the jungle has a certain eldritch quality to it. Together with the frightening sight it reminds me a bit of scenes from H. P. Lovecraft stories. One wonders if there was an influence, though Lovecraft would not be born until 1890 and as far as I am aware did not read much from Jules Verne. That said, both Verne and Lovecraft had Edgar Allan Poe as an influence. Getting back to the shore of the Lidenbrock sea, Otto and Axel find more signs of Arne Saknussemm, the Icelandic monk that led them to this journey. With their raft they follow his path, landing in another lava tube which ejects them out of the Italian volcano Stromboli, concluding their journey.

A few words on the hollow earth and dinosaurs

Despite the title, the protagonists of the Verne novel never reach the center of the Earth. According to Otto, the Lidenbrock Sea is “only” 35 miles (56.3 km) under the Earth. That is close to the boundary between the crust and the upper mantle, so admittedly still impressive, but very far from the center. In fact, at the end Axel is strongly of the opinion that his uncle still is a nutjob for thinking the Earth is hollow and that everything they encountered was nothing but local exceptions. Hence it is very ironic that this became one of the signature stories to influence hollow earth fiction. The idea of a hollow earth or at least large, underground lost worlds, did not begin with Verne. Arguably the oldest example of such a story was Dante Alighieri’s Divine Comedia from 1320, wherein at the center of Earth is hell with Satan himself. In a scientific context the idea was first suggested by Edmond Halley in 1692, when he postulated that the interior Earth is made up of multiple independently rotating shells with their own magnetosphere. He came to this conclusion as he tried to explain compass anomalies and the phenomenon of aurora borealis (which we now all know is actually caused by steamed hams). This was further adapted by Scottish mathematician Sir John Leslie, who proposed that there were two small suns in the interior of the Earth providing light to the surface of a concave hollow Earth. Leslie's idea is actually referenced by Axel when he first sees the Lidenbrock Sea. In 1818 John Cleves Symmes also hypothesized about a hollow Earth and proposed that entrances to it could be found at both the North and South poles. This actually inspired multiple arctic/antarctic expeditions trying to find these entrances. One of his most notable believers and approver of such an expedition was John Quincy Adams, the sixth president of the United States of America. Symmes’ theories also influenced The Narrative of Arthur Gordon Pym of Nantucket, an Edgar Allan Poe story from 1838. Despite all this popularity, the idea of a hollow Earth was already disproven in 1774, when Charles Hutton calculated the mean density of our planet, showing that its interior was filled and solid.

Verne’s true contribution to the genre was the connection between subterranean lost worlds and prehistoric life. In all previous stories the Hollow Earth was populated by either fantastic beasts or Atlantis-like civilizations. In my eyes it is clear that Verne himself did not believe in the Hollow Earth, but rather the mainstream geology of his time, and instead simply used this genre as a vehicle to tell a fun and also educational story about geology and paleontology, especially in a time when time-travel fiction did not really exist yet (Wells still had to catch up). I find the association between prehistoric life and underground worlds fascinating in a psychological and cultural context, as in many ways it resembles the reasoning behind ancient beliefs about the afterlife. Why did many old religions believe the world of the dead was underground (think of the Greek Hades or the Jewish Sheol) and not, say, on the Moon? A relative of mine who studied theology put it quite simply: That is where these cultures buried their dead, so it is where the souls of the dead would also stay and dwell. Now, why would prehistoric animals be living deep underground? Because that is where their fossils rest. To explain why these animals are only ever found as frozen carcasses, Siberian mythology actually does say that mammoths are animals which live continually underground like giant moles and once they accidentally breach the surface they instantly freeze to death. Similar stories exist in Native American folklore about fossils. Now compare this with Greek stories like that of Orpheus and Eurydice. The idea of meeting entities from the past while travelling underground was also used in Dante's comedy and various mythologies before him. In some ways the type of Hollow Earth which Jules Verne created then seems like a (subconscious) continuation of such ancient beliefs about the underworld. Images and scenes like the fossil graveyard and the coal mine only add to this baroque sense of remembering the dead (which in the end paleontology is all about when you think about it). However, any such deeper meaning seems to have been lost in later stories inspired by Verne’s novel. Edgar Rice Burroughs’ Pellucidar series, starting in 1914, and Vladimir Obruchev’s novel Plutonia from 2015 both feature a concave Hollow Earth populated by all sorts of prehistoric creatures (and occasionally Tarzan), but use these mostly as fantastical elements rather than being geologically or paleontologically minded. From then on the association with the Earth’s core and extinct life became codified without much sense behind it. The most hilarious example of this is the fact that, according to one of the screenwriters of the 2003 movie The Core (a movie which mind you is well aware that the interior of the Earth is solid and hotter than the sun’s surface), the original script of the film still wanted there to be dinosaurs at the Earth’s core! The movie is hilariously dumb as is, but I would have loved to see that trainwreck. Speaking of dinosaurs, it is odd that none appear in Journey to the Center of the Earth (apart perhaps from that one moa Axel dreams about). As a kid I thought this was simply because dinosaurs were not yet known in Verne's time, but history quickly proved young me wrong. The first known dinosaur, Megalosaurus, was already described in 1827, the Crystal Palace Park saw completion in 1853 and the relatively complete skeleton of Hadrosaurus was discovered in 1858. Édouard Riou himself previously illustrated a fight between Iguanodon and Megalosaurus in Deluge before working for Verne. In the next decade already the infamous Bone Wars between Marsh and Cope would break out. Why did Verne not capitalize on this growing dino-mania and instead resorted to fossil animals which were already long-known at the time? Frankly, I do not know. One also wonders if this “lack” had an influence on the book’s popularity over the years. While it is among his most well-known works, Journey to the Center of the Earth nowadays never seems to be as culturally relevant or popular as his other books, such as Around the World in 80 Days, 20’000 Leagues under the Sea or Around the Moon. Perhaps some dinosaurs would have helped boost its popularity. Though I think there is something deeper behind this. Most of Verne’s stories concern the technologies and possibilities of the present and future, while Journey stands out for being perhaps his only story that is interested in exploring the past. It is also mainly known for being both outdated and impossible. Compare it then, for example, with Around the Moon, which predicted many details of the Apollo moon landings with an almost eerie precision. As discussed previously this difference in popularity/relevance is likely indicative of the modern trend of young people being more interested in technology than fossils. But hey, when worlds collide...

On a final note, I really enjoyed the 2008 movie adaptation when I was younger. Brendan Fraser deserves more love, especially after what he has been through in recent years! This has been it for our first post in this new category. Next time we will take a look at Harry Govier Seeley’s Dragons of the Air from 1901. Thanks for reading and see you until then!

If you liked this and other articles, please consider supporting me on Patreon. I am thankful for any amount, even just 1$, as it will help me at dedicating more time to this blog and related projects. Patrons also gain early access to the draft-versions of these posts.

Related Posts:

• The Alien Prehistoric World Trope: Part 1 - Antediluvia
• The Alien Prehistoric World Trope: Part 2 - Dinosaurs become movie monsters
• The Paleoart of Spongebob Squarepants

Literary Sources:

• Ley, Willy/De Camp, Lyon Sprague: Lands Beyond, New York 1952.
• Verne, Jules:Journey to the Center of the Earth, Paris 1864 (German translated edition 1971).
• Witton, Mark: The Paleoartist's Handbook. Recreating prehistoric animals in art, Marlborough 2018.

Papers:

• Shafiee et al.: When will fossil fuel reserves be diminished?, in: Energy Policy, 37, 2009, p. 181 – 189.

Online Sources/Further Reading:

• The "palaeontological folklore" of mastodon hair and The science of the Crystal Palace Dinosaurs by Mark Witton.
• The Screenwriter Of THE CORE Responds!!
• What Ever Happened To Brendan Fraser?

The Many Mysteries of Darwin IV - Part 1

Fig. 1: The classic cover of the first edition, soon to be replaced by the reprint.

Ever since watching E.T. the Extraterrestrial, aliens were one of the biggest fears I had as a child. This was because most aliens I had seen since then were those weirdly humanoid ones, which are intentionally designed to evoke the uncanny valley. This fear of being abducted by greys or Spielberg’s roasted gremlin subsided when I saw two things: Star Wars, with its light-hearted and imaginative alien life, and a 2005 documentary on Discovery Channel called Alien Planet. Especially the latter made me see the idea of alien life in a new, positive light and gave me hope that we might discover some of it one day. What young me did not realize at the time (because who reads credits anyway?) is that Alien Planet was based off a science-fiction book by painter Wayne Douglas Barlowe. In Expedition a wildlife illustrator goes on a journey to a mysterious and wild planet called Darwin IV and paints the local creatures in all their beauty while detailing his travels. This book was first published in 1990, which means that this year marks its thirtieth anniversary! To commemorate the occasion, Barlowe is now selling a reprint of the book on Echo Point Books. If you never had the chance to read it before, now is your time! Now how do I want to commemorate one of the most monumental works in speculative evolution? By playing armchair-scientist of course!

One of the greatest strengths of Expedition is the great aura of mystery it not only creates but leaves behind about Darwin IV. After the first (and so far only) expedition we leave with more questions than we arrived with. This is what makes it feel almost real, as an actual first encounter with alien life would probably be just as if not more confusing. What I want to do in this post and its sequels is to seriously examine Darwin IV and the life on it in a semi-scientific way and maybe work out a few answers to its many mysteries. While I am doing this in part to put the knowledge I gained in studying Earth System Sciences to good use, my intention is also that we both learn something about real-life star systems, planets, geology and lifeforms in the process. This first post mainly concerns the orbital and geophysical characteristics of Darwin IV.

Fig. 2: The cover of the more well-known Alien Planet documentary, more precisely of the German DVD I owned since childhood.

Before we start, I just want to clarify that I will be very biased and apologetic about some of the criticisms made against the book by people in the spec-evo community. I just love Darwin IV so much that something deep inside me wants something like it to be real. When it comes to questions of plausibility, I will therefore play devil’s advocate (which is fitting since Barlowe has also extensively painted hell).

What does any of this have to do with dinosaurs or paleontology, you ask? You will see in time.

The Darwin System

Darwin IV is part of the Darwin star system. It is a binary star system 6.5 lightyears away, consisting of at least one F-type-main-sequence star and six planets (Barlowe 1990, p. 11-12). If both stars in this system are F-type stars is not exactly made clear, though they are said to be very different in size (p. 12). The real-life binary F-type star systems we know of that contain exoplanets are Upsilon Andromedae, Tau Boötis and HD 142 and in all three the second star is a red dwarf that circles the main F-type star. It is therefore safe to assume that the main Darwin star (let us call it Darwin A) is an F-type that is accompanied by a red dwarf (Darwin B). Now the first obvious question some of you may have is if a planet with large animal life could even exist in such a system. Our own sun is a G-type-main-sequence star. F-type stars can be up to 1.4 times heavier than our own star and are considerably hotter. Binary star systems can also lead to planets with unstable climates, depending on how they rotate which star. That said, Darwin IV’s stated position in the system actually makes its habitability quite plausible. There can be two types of planets in a binary star system: Non-circumbinary (S-Type) planets, which orbit only one star in the binary system, and Circumbinary (P-type) which orbit both stars at once if those stars are close enough to each other. Both types of planets can be habitable given the conditions, but P-types are more likely to be as they have more stable orbits. Darwin A and B are said to orbit so closely to each other that they look like a single star from one of their planet’s surface and Darwin IV orbits both of them at once, making it a P-type planet. Darwin IV being such a circumbinary planet may sound contrived at first, but there are multiple real-life examples of such circumbinary planets. Kepler-47c is one such example and even circles its binary system in its habitable zone. Speaking of which, Darwin IV is said to orbit Darwin A&B at a distance of two AUs or Astronomical Units (p. 12). One astronomical unit is the distance between Earth and our sun, in other words meaning Darwin IV is twice as far away from its sun(s) than we are from ours, which in our solar system would be about the position of the asteroid belt between Mars and Jupiter. Would that not mean the planet should be completely frozen over? No. Remember that F-type stars are larger and hotter than our sun. A 2014 paper determined that the habitable zone of an F0-type star (hottest in the F-class) extends from 2 to 3.7 AUs, while that of an F8-type star (coldest in the F-class) extends from 1.1 to 2.2 AUs (Sato et al. 2014). It is interesting to note that both these ranges are larger than our own sun’s estimated habitable zone which ranges from approximately 0.8 to 1.5 AUs. Darwin IV being 2 AUs away places it firmly well in the habitable zone of all F-type stars. Mind you that Wayne Barlowe accurately predicted this habitable zone 24 years before the study I cited was made. Because we do not know where in the F-class Darwin A is, it becomes difficult to say whether Darwin IV is comfortably in the middle or the rim of the habitable zone. We also are not informed (at least in the book) about the age of the system, which is also significant as the luminosity of a star changes throughout its lifetime. Depending on these two factors, Darwin IV might be (distance-wise) Darwin’s equivalent to Earth, but could also be its Venus, something to keep in mind. The same paper that estimated F-type stars’ habitable zones also determined that lifeforms around these stars are under stronger exposure to damaging UV-radiation, but this can be countered if the planet in question has an ozone-layer (something Darwin IV definitely has) and/or a decent magnetosphere (which it probably has).

Fig. 3: Darwin IV would be a P-type planet.

All that said, even if Darwin IV were not ideally or not at all in its star’s habitable zone, it could still be habitable for its lifeforms as we see. What many people forget or maybe just do not know when talking about habitable zones is that it just describes a region around a star in which without any modification or protection temperatures are in theory capable of maintaining liquid water and are tolerable for life as we know it. In other words, it is a zone determined by simply putting a blank thermometer into empty space and seeing where an astrophysicist would feel comfortable in his spacesuit. It does not take into account things like: Albedo caused by icecaps or clouds, greenhouse effects, densitiy and make-up of atmospheres and nuclear or tidal heating. As a consequence, some scientists consider the classic concept of habitable zones totally useless (Cohen 2002, p. 10) and I must frankly agree. The most poignant demonstration of this is Earth itself, as without its greenhouse atmosphere our temperatures would drop to minus 18 degrees Celsius on average, rendering most or all our surface water into solid ice. Temperature drops close to this have in fact happened billions of years ago, possibly suppressing the development of multicellular life for many millions of years. We are therefore, arguably, outside our solar system’s strictest habitable zone. More examples abound, such as Mars, which had plenty of liquid water on its surface at a time when the sun was at only 70% of its current luminosity, and the moons of the gas giants, far away from the sun but filled with liquid water thanks to the tidal forces enacted by their parent planets. According to calculations such as those by David Stevenson, even rogue planets which do not orbit any star at all but just wander through the eternal darkness of deep space could have liquid water on their surface thanks to a combination of an insulating atmosphere and geothermal heat produced by the decay of radioactive elements (Cohen 2002, p. 8). Even the other extreme, a planet way too close to its star, could have habitable conditions. Imagine for a moment if Mercury were tidally locked to our sun, (something we once used to think but then found out it rotated three times around its axis every two revolutions around the sun). One side would be infernally hot and the other permanently engulfed in cold darkness. Between these two unchanging extremes a gradient would span and inevitably at one point of this gradient a permanent ring would form around the planet on which, with enough air pressure, liquid water and life as we know it could exist… while at the same time farther away Venus would still be inhospitable (Cohen 2002, p. 131). So much for goldilocks zones…

At this point we might discuss what sources we should consider, as there is of course not just the book but also the documentary and its accompanying material. Bizarrely one of the most informative sources I could find about Darwin IV was of all things the brochure to my DVD of Alien Planet. I scanned a part of it here:

Now the first thing to note is that the orbital image here directly contradicts what is stated in the book, as Darwin IV is depicted as an S-type planet orbiting only one of the two stars and Darwin B is shown as similarly sized to Darwin A while also orbiting it at a significant distance. This makes little sense in the context of both the book and the documentary. The length of a Darwin IV-year is also given as 1.6 times that of an Earth-year, while in the book it is stated as being 2 Earth-years long (p. 12). The information given here should therefore not be taken as seriously as our main sources… which is unfortunate as the brochure also gives us information about three things which are not stated in either the book or documentary: The planet’s age (around 2 billion years old), density of the atmosphere (2 times that of Earth) and solar energy received (79% that of Earth). Especially the age and atmospheric density are pretty important, which makes it frustrating that they only come from an unreliable source. I will therefore treat these as estimates, but not necessarily canon. Also interesting is that we get a glimpse of planets Darwin I-III, all apparently larger than Darwin IV. Darwin V and VI are either outside the picture or do not exist in the documentary’s canon. Perhaps they got Pluto-ed.

One dense motherf...

Let us come to the orbital details and geophysics of Darwin IV itself.  As mentioned, going by the book’s information, a full rotation of the planet around its two stars takes about 2 earth-years, so about 730 earth-days. A single day on Darwin IV lasts 26 hours and 42 minutes (p. 12). A Darwinian year therefore lasts about 656 Darwin-days. This is comparable to Mars, whose days last 24h39min and whose year is about 1.8 times as long as that of Earth.

Fig. 4: Physical characteristics of our inner rocky planets. Darwin IV has similar dimensions as Mars, but might internally be structured more like Mercury.

A further similarity between Mars and Darwin IV is that they are small compared to Earth. Earth has an equatorial diameter of about 12’756 kilometers, Mars one of 6792 km and Darwin IV one of 6563km (p.11). This translates to respective volumes of 1.08321 x 10¹² km³, 1.6318 x 10¹¹ km³ and 1.48015 x 10¹¹ km³. In other words, Darwin IV has about 51% of Earth’s diameter and only 13.6% of its volume, while sharing almost 97% of Mars’ diameter and 90.7% of its volume. From that we would assume that Darwin IV has a similar mass and density to Mars and therefore also a similar gravity. Gravity is usually measured in gravitational acceleration, which on Earth measures about 9.8 m/s² (1 g) and on Mars 3.72 m/s² (0.38g or 38% of Earth-gravity). Now, directly from the text, the gravity of Darwin IV is described as being 60% that of Earth (p. 12), which would mean it has a gravitational acceleration of about 5.88 m/s². Here we meet our first major mystery. How can Darwin IV be smaller than Mars yet have considerably higher gravity? This must mean it has a higher mass and, due to its size, a way higher density. We can determine the mass of Darwin IV if we multiply its gravity acceleration (5.88) with the radius squared (3281500²) and divide this by the gravitational constant (6.673 x 10^-11), giving us a value of 9.48858 x 10²³ kg. That is about 15.9% the mass of Earth but over 146% the mass of Mars! If we divide this mass through the volume of the planet (1.48015 x 10²⁰ m³) we get a density of 6410.55 kg/m³ or 6.41 g/cm³. That is higher than the density of the Earth, which measures only 5.51 g/cm³! Coincidentally Earth happens to be the densest object in our solar system, meaning Darwin IV is denser than any of our planets. The closest analogy we could compare it to is the planet Mercury. Despite being a lot smaller than Mars, Mercury has a density close to that of Earth with 5.43 g/cm³, making it the second-densest object in the solar system (if we correct Earth’s value from gravitational compaction, Mercury would actually be number 1). The hypothesized reason for that is that Mercury’s inner iron-rich core must make up around 55% of its volume, compared to Earth’s which only makes up 17%. The safest assumption is therefore that Darwin IV’s core makes up a similar proportion of its volume. Determining the exact radius of this core and the rest of the planet’s internal structure is however difficult without having seismological data as we have for Earth. A more pressing question is perhaps how Darwin IV ended up with such a proportionally large core. Three proposed explanations exist for Mercury’s situation:

• Mercury used to be larger in the past but a giant impact early in its history stripped off much of the crust and outer mantle, leaving only the planetary core and little else behind.
• Due to its proximity to the sun the lighter elements of Mercury’s outer layers essentially vaporized and then were stripped off the planet by solar wind.
• During the formation of the solar system, the solar wind of the proto-sun pushed away low-density material from the innermost orbits, leaving Mercury with only high-density material to form out of.

Current surface-data obtained by satellites does not support the first two hypotheses, leaving the last one as the likeliest. Darwin IV is however too far away from its suns for hypotheses II and III to work, unless maybe the planet used to be a lot closer to its parent-stars in the past but then wandered farther out. Such behaviour has been proposed for gas giants, but does not seem likely for rocky planets, so we may assume that Darwin IV formed at roughly its current position. The possible explanations we are therefore left with are either a giant impact or the possibility that planet-formation around F-type stars simply does deal with denser materials than we are used to in our G-type system. I unfortunately could not find any sources about the latter topic, though the higher energy output of F-type stars might result in denser material at farther distances than is normal for our system, meaning a modification of hypothesis III could still work. All that said, the best guess for our subject so far is the impact-hypothesis. The best evidence we might have for it are Darwin IV’s two moons. Not much is said about them, but we can see both of them in the Darwinian sky on plate XXVI (p. 136.) and on the original edition’s cover. Unlike the two moons of Mars, Phobos and Deimos, the Darwinian moons (let us call them Wallace and Lamarck because why not) appear perfectly circular in shape like our own moon. This means they both have reached hydrostatic equilibrium or in other words have enough mass that gravity squishes them into spheroids. The smallest known object with hydrostatic equilibrium is the dwarf planet Ceres, so the moons must be at least that massive. However, since Ceres is mostly made of ice and the Darwinian moons are (probably) mostly made of rocks, it means they are likely considerably heavier. That is a suspiciously high amount of mass in Darwin IV’s orbit. It is not impossible that these moons used to be dwarf- or proto-planets that Darwin IV captured with its surprisingly strong gravity, but you probably guessed what I am getting at here. It seems just as plausible that during its formation a younger, larger Darwin IV was hit by another proto planet, just like Earth was. This impact would have however been considerably more violent than ours, stripping away much of the outer layers of the planet and scattering them into orbit where the debris could develop into fully fletched moons. This impact, perhaps in combination with a higher density of the impactor, fusing of the two cores and/or a generally high density of the Darwin-proto-planetary-disk, led to the formation of the current small and dense Darwin IV.

Fig. 5: The two moons of Darwin IV as seen from its northern tundras.

With these assumptions we will then move on to part 2 where we will examine the geography, geology and atmosphere of the planet. Thank you so much for reading and see you until then.

If you liked this and other articles, please consider supporting me on Patreon. I am thankful for any amount, even just 1$, as it will help me at dedicating more time to this blog and related projects. Patrons also gain early access to the draft-versions of these posts.

Related Posts:

• The Alien Prehistoric World Trope: Part 6 - Just Plain Barlowe

Literary Sources:

• Barlowe, Wayne: Expedition. Being an account in word and artwork of the 2358 A.D. voyage toDarwin IV, New York 1990.
• Barlowe, Wayne: The Alien Life of Wayne Barlowe, Beverly Hills 1995.
• Cohen, Jack/Stewart, Ian: Evolving the Alien. The Science of Extraterrestrial Life, London 2002.
• Costard, François/Forget, François/Lognonné, Philippe : Planet Mars. Story of Another World, Paris 2006.
• Grinspoon, David Harry: Venus Revealed. A New Look below the Clouds of our Mysterious TwinPlanet, Cambridge 1997.

Papers:

• Sato et al. 2014: Habitability around F-type stars

Online sources/Further reading:

• COULD ALIEN LIFE COPE WITH A HOTTER, BRIGHTER STAR?
• Messenger sheds light on Mercury's formation

Image Sources:

• Fig. 1: Barlowe 1990, cover.
• Fig. 3: Wikimedia
• Fig. 5: Costard 2006, p. 24.
• Fig. 6: Barlowe 1990, p. 136.