Friday 19 February 2021

Gresslyosaurus: The Eldritch Dinosaur that turned its Discoverer insane?

Fig. 1: Yours truly at the Zoological Museum of Zürich, standing next to a model of Plateosaurus engelhardti, a dinosaur that may or may not be similar to Gressylosaurus, though read on (Image taken by my girlfriend).

For a project of mine I may or may not be working on, I have lately been researching various fossil discoveries made in Switzerland. I have undoubtedly come across some major surprises, for example the discovery of a genuine terror bird, so far the only legit one from Europe, in Egerkingen. Today I will however talk about the somewhat disconcerting history of the little-known genus Gresslyosaurus. The first time I heard of its name I admittedly had to grin a little, as Gressly sounds a bit like “grässlich”, the German word for awful. Gressly is however the name of a person, Amanz Gressly, who dug the bones of this dinosaur out in Niederschöntal (today Füllinsdorf) in the Kanton of Basel-Landschaft and sent them to Ludwig Rütimeyer in the year 1856. To give you a feel for the time period, Switzerland under its current constitution was by that point only eight years old, having recently survived a civil war and the rule under Napoleon. Rütimeyer at first thought these bones belonged to Belodon, a genus of phytosaur, but in 1857 announced that these remains actually represented the first dinosaur fossils known from Switzerland. To honor its discoverer he named the species Gresslyosaurus ingens. Similar to the prosauropod Efraasia it was originally considered a relative of Teratosaurus, a genus infamously thought to have either been the first “carnosaurian” theropod or a large, carnivorous prosauropod, until in the 1980s it was realized to have actually been a rauisuchian crocodile-relative. In the following decades at least three other species were assigned to Gresslyosaurus, G. plieningeri, G. robustus and G. torgeri. The reason why most of you have probably never heard of this genus is Peter Galton, who in 1986 re-examined the bones excavated by Gressly and concluded that the genus is synonymous with the already known species of Plateosaurus, a dinosaur in Switzerland now better known from the Gruhalde quarry in Aargau. This has been generally accepted by workers ever since those days.

Fig. 2: Rütimeyer’s original sketches of the Gresslyosaurus fossils.

But who was Amanz Gressly, the discoverer of these fossils? Born 1814 in Bärschwil, Kanton Solothurn, Gressly originally studied medicine, but in 1834 decided to instead follow his true passion, geology. He taught himself the practice entirely autodidactically and together with friends amassed an impressive private collection of fossils. His personality was generally described as very odd and shy, but also exceptionally intelligent, nice and cordial. While I am definitely not an expert on these matters, based on some of the descriptions it seems plausible that today Gressly’s personality might be placed somewhere on the autism-spectrum. Louis Agassiz, well known for discovering the existence of the ice ages as well as his work on fossil fish, became aware of Gressly and his collection when the latter moved to Neuchatel in 1836. He decided to make Gressly his assistant, borrowing some parts of his collection for his works and even naming the clam genus Gresslya after him. During his time as Agassiz’s assistant Gressly wrote Observations geologiques sur le Jura Soleurois in 1841, which was significant for the history of geology, as in it Gressly was the first scientist to use and define the term facies (used to describe the general characteristics of a rock layer), which laid the groundwork for all later stratigraphy. In the same work he also gave birth to the study of biostratigraphy and paleoecology, discovering that the Jurassic mountains once used to be a shallow sea of reefs. Unfortunately, the completion of this work left a heavy toll, as Gressly suffered a mental breakdown shortly after, which his mental institution made him recover from through an extended stay in the city of Solothurn. Meanwhile, between the years 1833 and 1844, Louis Agassiz had been working on Recherches sur les Poissons Fossiles (Research on the Fossil Fish), a monumental five-volume treatise, which also included parts of Gressly’s collection. The production, illustration and printing of this project made Agassiz accumulate a massive debt and instead of paying off said debt, he fled Switzerland and departed to the United States of America in 1846, founding the Museum of Comparative Zoology at Harvard University. During his last years in America Agassiz became most well-known for his unflattering influence on “scientific” racism, such as his ideas on multiregionalism (the notion that the human ethnicities all independently evolved from each other out of different ape species), and also his critiques of Darwinian evolution. In case you were not convinced yet that Agassiz was a less than amicable person, during his exodus to the States he also took with him some of the best fossils from Gressly’s collection, apparently without the consent of the owner. This betrayal by his former mentor and idol burned Gressly out on Neuchatel, already disliking the city for many years (relatable), making him leave it shortly after. The following ten years he spent his life as what can only be described as a nomadic scientist, travelling through, and apparently even living in the wild parts of the Jurassic mountain side, studying rocks and fossils and only settling down for short times in Solothurn and surrounding cities to write and publish papers on what he had found. In these years this wild scientist of the mountains became beloved by the local populace and his colleagues, his sloppy clothes and wild-growing beard becoming his trademark. His obituary in the London Geological Magazine makes him almost sound like a real-life Gandalf:

He was a child of the people, loved and known by all. Possessing vast knowledge and most profoundly acquainted with the structure of our mountains, yet was he simple and unostentatious. Gressly had no enemies, envy and jealousy had no place in his heart; he was, as it were, an echo of another age. No one was more popular than he in the Jura; from the Perthe-du-Rhône to the Rhine there was not a village in which he did not count friends, and where his arrival was not saluted with acclamations.” (Stampfli 1986, p. 19).

In the 1850s his Enkidu-years came to an end as he was hired by the Swiss Central Railway as a geologic surveyor. The geologic profiles he made were integral to the construction of the Hauensteintunnel, one of the oldest railways in Switzerland. During his years working for railway-projects in the alps, nearly all his geologic predictions were proven correct during the tunnel constructions, even earning him the respect of the Geological Society of London. The beginning of the 60s Gressly spent with travelling to Southern France as well as Iceland to study, respectively, their marine life and geology.

Fig. 3: Amanz Gressly with his trademark beard. The photograph was taken in the 1860s, when he had become more sedentary again.

Unfortunately, the story does not have a happy ending. Throughout his life Gressly had been plagued by mental health issues, his breakdown in 1841 only being one of many. In 1864 he had to go into treatment at the Universitäre Psychiatrische Dienste Bern, commonly referred to as the Waldau. What exactly he was suffering from is hard to say nowadays, as the study and treatment of mental disorders was still very rudimentary in the nineteenth century. The Waldau was commonly referred to as an Irrenhaus, meaning a lunatic/insane asylum, which at this time would have mainly been occupied with keeping its patients away from society, rather than giving them therapy and rehabilitating them. One of the few accounts of his life there and the reason why I am even writing this article, I discovered by complete coincidence. It comes from Die Urwelt der Schweiz (The Primeval World of Switzerland), written by Oswald Heer. Heer was a well-renowned paleobotanist and entomologist working at the University of Zürich and the Polytechnikum (which would later become the ETH) as well as a big idol to none other than Charles Darwin. His book, originally published in 1865, is a monumental work which details the geologic and fossil record of the country known at the time from the Coal Age all the way to modern day. It is also filled with tons of great paleoart by the author, even if most of it consists of plants, landscapes and bugs. In the passage describing animals from the Triassic he wrote a few sentences about Teratosaurus and how a fossil found by Amanz Gressly, the Gresslyosaurus, is likely the same animal. In what is merely a footnote he then mentions:

Der arme Gressly, welcher in Wahnsinn verfallen, ins Irrenhaus gebracht werden musste, wurde von dem Gedanken gequält, dass er in diesen Gresslyosaurus verwandelt worden sei.(Heer 1865, p. 66).

Which means translated:

Poor Gressly, who, falling into insanity, had to be brought to the lunatic asylum, was agonized by the thought that he had transformed into this Gresslyosaurus.

Heer does not provide a source for this claim, but considering that he knew Gressly personally, he is likely telling some version of the truth here, which has absolutely disturbing implications. The discovery of Gresslyosaurus was perhaps one of the most minor parts of Gressly’s life, so how come then that this dinosaur occupied such a large part of this person’s mind, that in an unstable state he came to think he had turned into it?! Was it simply because the dinosaur was named after him or was there something more bizarre going on? Was it something about the bones or the circumstances of the discovery itself? There is something very eerie about all of this, an untold backstory that a talented writer could probably construe into Lovecraftian dimensions. We may never know what has led to these circumstances, as Gressly took the secret with him to the grave. After initial improvements, he died on the thirteenth of April 1865 of a stroke, still at the Waldau. He was buried in Solothurn, where he liked to reside the most, his gravestone reading:

Gresslius interiit lapidum consumptus amore,

Undique collectis non fuit hausta fames.

Ponimus hoc saxum. Mehercle! totus opertus

Gresslius hoc saxo, nunc satiatus erit.”

Which roughly means:

Here lies Gressly, who died through his odd love of stones,

Which he collected in his house, but did not satiate his hunger.

Let us place this stone. By God! Covered whole in stone,

Lying between stone, Gressly now has enough stones.


Fig. 4: A megalith in the Verena Hermitage Gorge, with an engraving honoring Amanz Gressly. Yes, you read that right, a megalith. According to info-plaques at the place, the rock itself was not placed in Gressly’s honor but was erected inside the gorge in ancient times by iron age people, presumably Celts (Image taken by me).

Gressly is still beloved and well-remembered by Swiss paleontologists and geologists today. Multiple memorials have been erected in his honor throughout Kanton Solothurn, one of which you can see above. Even a street is named after him. Since 2004 the Schweizerische Paläontologische Gesellschaft gives the Amanz-Gressly-Award to people who have done extraordinary work in paleontology. In 2020 the sauropod Amanzia greppini was also named after him (the species name honoring Swiss paleontologist Jean-Baptiste Greppin). Up to that point this species, which was found in Moutier, Kanton Bern, was originally classified as Ornithopsis greppini, before that as a Cetiosauriscus and even before that as a Megalosaurus, as an associated Ceratosaurus tooth was once assumed to be part of the same animal. As for the fate of Gresslyosaurus? Galton’s assessment that the genus is the same as Plateosaurus was not accepted uncritically, already being criticized in 2003 due to significant differences in the vertebrae. In 2020 Oliver Rauhut and Heinz Furrer re-examined a load of prosauropod bones from Schleitheim, Schaffhausen, which had previously all been labelled Plateosaurus and were then largely forgotten. In their analysis they identified and named a completely new species among the remains, Schleitheimia schutzi, which unlike Plateosaurus was a quadrupedal sauropodiform very close to the origin of true sauropods (and also considerably larger). In the same paper they also re-examined the Gressly fossils and noted that, while the data is very fragmentary, the fossils do indicate a prosauropod that was very distinct from Plateosaurus and either was its own genus or is possibly synonymous with Schleitheimia (in the latter case the name Gresslyosaurus would have priority due to being older). The bones are currently being re-preparated for further study, but until then it does seem like the taxon is indeed valid again, in one form or another. In other words:


Gresslyosaurus has risen from the grave!


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Literary Sources:

  • Hartmann, Alfred: Amanz Gressly, in: Gallerie berühmter Schweizer der Neuzeit. Band 1, Baden 1868.
  • Heer, Oswald: Die Urwelt der Schweiz, Zürich 1865 (2. Edition 1883).
  • Rieppel, Olivier: Mesozoic Sea Dragons. Triassic Marine Life from the Ancient Tropical Lagoon of Monte San Giorgio, Bloomington 2019.
  • Stampfli, Hans: Amanz Gressly. 1814–1865. Lebensbild eines ausserordentlichen Menschen, Solothurn 1986.


Image Sources: