Swiss Dinosaurs: Everything we know so far (Triassic)

Fig. 1: My speculative reconstruction of Gresslyosaurus ingens.

Some countries are well-known for their fossil finds. For a long time, some of the most famous dinosaurs almost all came from the USA and today the news is rife with weekly spectacular finds from China, Brazil, Argentina or Morocco. In contrast, even though the first ever dinosaurs were scientifically described here, European countries have taken more of a backseat in dinosaurology. This is especially true for Central Europe, including Switzerland. There are both geological as well as historical reasons for this. Mainly, the landmass that would one day become Switzerland was (ironically for a landlocked, mountainous country) largely submerged beneath the ancient Tethys Sea for most of the Mesozoic. As dinosaurs were terrestrial animals, most of the Swiss Mesozoic record thus filled with marine or flying creatures. Mesozoic Switzerland was mainly ichthyosaur-country (which you will hopefully soon learn more about once a paper I co-authored has passed peer-review). Due to the heavy erosion caused by the Alpine and Jura orogenies, spectacular bonebeds and Lagerstätten, such as those of North America, are also rare. The most prominent one is the Grenzbitumenzone of Meride in Kanton Ticino, today an UNESCO world heritage site, but it dates to the Middle Triassic (before true dinosaurs had even evolved) and thus yields us “just” protorosaurs like iconic Tanystropheus and various other marine weirdos.

However, the mere idea that dinosaurs are not to be expected here, despite first finds dating back all the way to 1856, may have also influenced a lack in research. Since the 90s it has been crystal clear that some parts of Switzerland were dry during the Mesozoic and they were walked on by dinosaurs. While the record of actual body fossils may be meagre, Northern Switzerland, especially the region of Jura (from which the Jurassic period derives its name) has become a hotbed for fossil trackways, showing that a remarkable diversity of taxa must have existed here at one point not too dissimilar from the faunas that existed in Iberia, Morrison and the Tendaguru Beds. Switzerland was also a dinosaur country, even if the evidence is not as obvious at first glance.

For the new upcoming exhibit at the Zoological Museum of Zürich I was tasked with designing a new vitrine for the dinosaurs of Switzerland (replacing the old one which was outdated and rather sparse). I thought it would be fun to share everything I have discovered on the way and then some more. In this part we will take a look at everything that can be said about the Triassic period, when large sauropodomorphs and small theropods fought with pseudosuchians for hegemony over Pangea.

Body fossils

Body fossils of Swiss dinosaurs are rare, mostly incomplete and restricted to the Triassic and Jurassic (unless we count birds of course). A major exception is the clay-pit of Frick in Aargau, which has yielded multiple almost complete skeletons of Plateosaurus, as well as remains of theropods and other Late Triassic life. During the Late Triassic there were various periods when most of Northern Switzerland was land, though various marine incursions occurred during multiple stages. During dry times, the climate was arid, only wettened by some rivers, mudholes and sabkhas. In addition to saurischian dinosaurs can also be found various marine reptiles (including titanic ichthyosaurs), campylognathoid pterosaurs, pseudosuchians, temnospondyls and cynodonts.

What seems to be completely lacking is any identifiable remains of ornithischian dinosaurs. Depending on what hypothesis for ornithischian-origins you ascribe to (such as Ornithoscelida), this may be not too surprising. Some teeth from the Rhaetian of Hallau, Kanton Schaffhausen, were once identified as belonging to a heterodontosaurid, but further reassessment found them to not be identifiable beyond Archosauriformes indet. (Butler et al. 2006)

Gresslyosaurus

Fig. 2: The original dinosaur bones found by Amanz Gressly.

The first dinosaur fossils identified in Switzerland were discovered in 1856 by Amanz Gressly in Füllinsdorf, Basel-Landschaft. Originally thought to come from the phytosaur Belodon, Ludwig Rütimeyer correctly identified the remains the following year as those of a dinosaur, which he named Gresslyosaurus ingens. It was originally thought to be an animal similar to German Teratosaurus (Heer 1883), which was for a long time interpreted as a Triassic “carnosaur” (as in the old definition of all large theropods, from megalosaurs to tyrannosaurs, forming a monophyletic group contrasting with the small coelurosaurs, not the modern usage of the Carnosauria clade that’s allosauroids+megalosauroids) or even a carnivorous prosauropod. Since the 1980s it is known that Teratosaurus was actually a rauisuchian crocodile-relative and had nothing to do with Gressylosaurus or dinosaurs in general. Despite various more fossils and species across Europe being assigned to Gresslyosaurus, American paleontologst Peter Galton (1986) concluded that it was a synonym of Plateosaurus, an opinion that has been followed ever since, though not without criticism (see Moser 2003). In their description of Schleitheimia schutzi from material once referred to Plateosaurus, Rauhut et al. 2020 also took a look at the original Gressylosaurus material and concluded that Galton was wrong, it too not being referrable to Plateosaurus. The material is currently still being restudied, but based on their findings, what can be said is that it was a sauropodiform likely very similar to Schleitheimia, meaning a large, quadrupedal animal already approaching the true sauropod-bauplan, not a more archaic biped like Plateosaurus. If future work recognizes Gresslyosaurus and Schleitheimia as synonymous (and the original remains are diagnostic enough), then the former’s name would take precedence, but at the moment they seem to have been distinct (Rauhut et al. 2020). So far almost no paleoart exists of the taxon. According to Oswald Heer, late into his mental illness, Amanz Gressly believed to have been transformed into his dinosaur.

Plateosaurus

Fig. 3: My reconstruction of Plateosaurus (based on a skeletal by Scott Hartman). Originally drawn for my book.

Perhaps the most well-known dinosaur of the whole country, Plateosaurus trossingensis (which has become the type species for the genus after the original P. engelhardti was found to not be diagnostic enough anymore) is a famous species also known from Germany, whose research history stretches all the way back to 1834. Most Plateosaurus fossils come from the Gruhalde Quarry in Frick, which has yielded complete skeletons of both adult and juvenile specimens. These likely stem from herds which, during the dry season, came to a watering hole and became mired in mud, though this hypothesis has been questioned from time to time. The Gruhalde Quarry contains multiple dinosaur-bearing layers (6 in total), spanning throughout the Norian, plateosaur bones being the only ones consistently found in all of them. Due to this longevity, it is doubtful if all of these bones are from just  P. trossingensis, which they have traditionally been assigned to, and more likely that they represent different species of Plateosaurus (Zahner 2023). Plateosaurus is such a well-known genus that there is not much novel information about its biology to add here. What is notable is that, due to a period of lumping since the 80s, the genus has been somewhat of a wastebasket for various Swiss sauropodomorph remains, leading to genera like Gresslyosaurus and Schleitheimia going unrecognized for a long time. Perhaps even more taxa might be hiding inside the known Plateosaurus material. Teeth from Corbeyrier in Kanton Vaud have also been referred to Plateosaurus, but these could have also come from phytosaurs (pers. comm. with Christian Meyer).

Liliensternus

Fig. 4: My rendition of Liliensternus (referenced from a skeletal by Greg Paul).

Various teeth and bits of bone from Kt. Aargau have historically been referred to Liliensternus liliensterni (Sander 1992, Meyer & Thüring 2003). A large tooth from Hallau in Schaffhausen, once referred to Megalosaurus (Schalch & Peyer 1919), is probably also from a Liliensternus-type theropod. Due to their fragmentary nature, I personally find it a little questionable to say that these remains definitely came from Liliensternus, but it still would not be wrong to assume that this taxon existed in Switzerland, as, like Plateosaurus, it is originally known from Southern Germany. There is nothing that speaks against both dinosaurs having inhabited the same range, especially as there was no natural barrier between what would become Germany and Northern Switzerland, so, unless another Central European theropod of similar size and age is discovered, calling these remains Liliensternus seems pretty reasonable. For what it is worth, the 2018 theropod bones of specimens SMF 18-8, from the middle dinosaur horizon of Frick, and the slightly older SMF 23-3 show a great resemblance to Liliensternus liliensterni, with minor differences perhaps being attributable to just geologic deformation (Zahner 2023).

About 5.2 metres long, Liliensternus was among the largest theropods of its time, though I still find it doubtful that it could have taken down a full-grown Plateosaurus trossingensis, as is often shown in paleoart (people underestimate just how massive that dinosaur was). Apart from other theropods, its major competition must have been rauisuchians like Teratosaurus, which may have grown even larger. Liliensternus’ skull is not completely known, so there have mainly been two traditions in depicting it: A crestless version that looks like a Coelophysis on steroids and a crested version that looks like a more gracile Dilophosaurus. Indeed, a once popular idea by Greg Paul (1988) was that Liliensternus was a transitional form between Coelophysis and Dilophosaurus, all three included within Coelophysidae (which, as a side-note, he thought gave rise to the Spinosauridae due to both sharing a kinked snout). While elegant, modern cladistics does not support such a family tree anymore. Coelophysoidea appears to be a distinct early branch of Neotheropoda, while Dilophosaurus is a closer relative of the more derived Averostra. Where exactly this leaves Liliensternus seems to still be a bit uncertain.

Notatesseraeraptor

Fig. 5: My reconstruction of Notatesseraeraptor, based on the skeletal from the original description (though I corrected the arm posture, which was anachronistically pronated in the paper). Because I chose a lipped design, the snout-kink is not as prominent as the skeleton would suggest.

Notatesseraeraptor frickensis represents the first theropod taxon so far only known from Switzerland. Its skeleton was already discovered in 2006, from the uppermost dinosaur-layer of Frick (Late Norian), by hobby-paleontologist Michael Fischer, but it took until 2019 for it to be fully described and named. Originally thought to have been a coelophysid, said description (Zahner & Brinkmann 2019) recovered it as clearly having been on the neotheropod line leading towards Averostra, making it a closer relative of Dilophosaurus and Zupayasaurus. The name Notatesseraeraptor means something like “mosaic-trait-thief” and refers to its mosaic of skeletal characteristics from both coelophysids and “dilophosaurids”. Due to its unwieldiness, I and some people in the field have bemoaned the name choice, though I guess something like “Frickosaurus” would have probably led to immature sniggering from Americans (“frick” being mistaken as the family-friendly replacement for the F-word).  

Fig. 6: A more traditional, but great life model of 'Tessie and its last meal, made by Beat Scheffold (Image taken by me).

The amazing holotype includes most of the front part of the skeleton as well as a complete skull. Even stomach content was preserved, showing that the animal’s last meal was a small rhynchocephalian, Clevosaurus. It is one of, perhaps even the most complete theropod skeleton of Late Triassic Europe. The living individual is estimated to have been 2.6 to 3 metres in length, but many signs point towards it having been a sub-adult. Adult N. frickensis were perhaps closer to 4 metres long.

Schleitheimia

Fig. 7: A beautiful reconstruction of Schleitheimia, again by Beat Scheffold. Also shown are other critters known from the Swiss Triassic.

The bones of Schleitheimia schutzi were technically known since the 1950s, having been collected by Emil Schutz from Norian layers of the Klettgau Formation in Schleitheim, Kanton Schaffhausen. However, they were stored away and largely forgotten in museum archives due to, as mentioned above, having been identified as just some more Plateosaurus bones. Rauhut et al. 2020’s analysis of these bones showed that it was actually quite a different beast. Schleitheimia was a huge sauropodiform, related to taxa like Isanosaurus and Gongxianosaurus, sitting very close to the origin of the true Sauropoda. That is, Sauropoda in the sense of Gravisauria, but depending on broader definitions of the clade, Schleitheimia may already be called an early sauropod. While the remains are incomplete and the authors did not provide a skeletal, we may thus imagine a large, quadrupedal animal that already foreshadowed the future titans of the Jurassic. In that regard, the above illustration by Beat Scheffold may be a bit too conservative in showing the animal as looking like a quadruped plateosaur, when it may have resembled more animals such as Antetonitrus.

Of course, the existence of a true sauropod from as early as the Norian may come as a surprise to some, but as we will see it actually lines up pretty well with trackway evidence from other parts of Switzerland.

Unnamed Frick Coelophysoid (SMF 17-1)

Discovered in 2017 and described in 2023 as part of Marion Zahner’s doctoral thesis were postcranial bones of a small theropod, coming from the lower dinosaur horizon of the Frick locality. The individual was even smaller and younger than the N. frickensis holotype, perhaps being only a year old at the time of death. That it was a juvenile of N. frickensis was considered by Zahner, but deemed unlikely as the former comes from the topmost layer of the Norian Gruhalde Member, while the new specimen comes from the second-lowest one, meaning that potentially as much as 20 million years could be separating the two. Furthermore, SMF 17-1 shows much greater similarity to true coelophysoids, such as Coelophysis and Megapnosaurus, making it much more likely to be a true member of that clade rather than an averostran-line theropod like Notatesseraeraptor. 

Fig. 8: A generalized coelophysoid (based off Coelophysis bauri)

Due to being incomplete and lacking cranial remains, Zahner refrained from assigning the remains to any known genus or even erecting a new taxon. Personally, I wonder if this animal is in some way related to Procompsognathus triassicus, a coelophysid from Bavaria that, like Liliensternus, could have very well also existed in Switzerland. They probably are not the same, however, as adult Procompsognathus were only a metre long, whereas SMF 17-1 seems to have already been larger than that as a juvenile.

From the same layer as SMF 17-1 and only 2 metres away were discovered the remains of another small dinosaur (SMF 17-4-133), but Zahner considers it unlikely that they come from the same individual, as the sizes of the vertebrae do not match between specimens. Until further preparation is done, not more can be said about this specimen other than that it was a saurischian.

Unidentified mini-prosauropod

From the lowest known dinosaur layer of Frick, close to the Carnian-boundary, were found in 2021 remains of a bipedal sauropodomorph that has yet to be officially described (Zahner 2023). It is very much unlike Plateosaurus, being small with gracile limbs and hollow bones (Zahner 2023). If true, the latter trait would be quite significant, as skeletal pneumaticity in early sauropodomorphs has so far been ambiguous, leading some to think that true sauropods evolved this trait independently of theropods.

Trackway Record

Whereas the body-fossil record of the Swiss Triassic is rather impressive, the ichnological record is sparser, which is the opposite condition of the Swiss Jurassic. While there are many Triassic vertebrate footprints known throughout the country, most of them seem to have been produced by pseudosuchians, being of the Chirotherium or Isochirotherium type, such as the trackway from Vieux Emosson that proved that the northern coast of the Vindelician Land once stretched all the way into Kanton Vaud (Avanzini et al 2009). These were likely made by quadrupedal animals very similar to Ticinosuchus. Intriguing are small Chirotherium-type footprints from the Carnian of the Tödi mountain (uncovered from beneath glacial ice thanks to climate change), which lack handprints and therefore suggest the trackmaker to have been bipedal (Feldmann & Heinz 2008). Perhaps a sort of mini-Postosuchus?

Fig. 9: Trackways from Piz Mitgel, showing tracks of four-toed prosauropods and small theropods.

Actual dinosaur tracks are largely restricted to Kanton Graubünden, which is geographically and geologically distinct from Northern Switzerland, specifically its national parks and reserves. Despite being far away from where we know the northern dinosaurs to have lived, their form and classification suggests that they were produced by dinosaurs very similar to (and probably the same as) the ones mentioned above. This is again in contrast to the Jurassic record, which tends to preserve footprints of dinosaur groups entirely unknown from body fossils. Interestingly, despite living at the same time there is so far no site where the aforementioned rauisuchian tracks co-exist with dinosaur ones (Meyer at al. 2019). Perhaps that means they lived in different habitats?

Kayentapus minor

From the Piz Mitgel and Piz dal Diavel come footprints similar to the ichnotaxon Grallator, each about 17 – 25 cm in length (pers. comm. with Christian Meyer says they should be classified as Kayentapus minor). These are a dead-ringer for small theropods. There are fortunately some quite neat calculations to determine the approximate sizes of theropod trackmakers based on the footprint sizes. You can take the length and raise it by the power of 1.14. The result you then multiply by 3.06, which gives you the height of the hip (Weems 2006). Less accurate, but simpler, you can also just multiply the footlength by 4 (Martin 2014). If you multiply this number again by 4, you get the approximate length of the dinosaur. In this case, the trackmakers would have been about 2.7 – 4 metres long, which fits perfectly with a dinosaur similar to Notatesseraeraptor.

Eubrontes

Fig. 10: Trackways of a large theropod from Piz Ela.

Also from the Piz Ela come prints resembling Eubrontes, about 28 – 33 cm in length. It is unclear if these were produced by a theropod or a sauropodomorph (Marty et al. 2013), but the approximate size of the trackmakers, up to 5.2 metres long, would fit a theropod like Liliensternus quite well.

Tetrasauropus

Known from the Late Norian of Piz Mitgel, Piz S-chalambert and Spi da Tantermozza are large footprints, about 50 - 70 cm in length, which resemble the classic ichnotaxon Otozoum (Meyer et al. 2019) but are perhaps better classified as bipedal variants of Tetrasauropus or Pseudotetrasauropus (pers. comm. with Christian Meyer). Ironic, given the name. Preserving no handprints, these were likely produced by large, bipedal prosauropods, meaning most likely plateosaurs.

Sauropodiformes indet.

Fig. 11: Fooprints of a sauropod or near-sauropod from the Kössen Formation of Val Gravaratschas. The same formation has also yielded the bones of the pterosaur Caviramus and vertebrae from gigantic, whale-sized ichthyosaurs.

Known from the Latest Norian and Rhaetian of Piz S-chalambert and Val Gravaratschas are various overlying layers of tracks produced by quadrupedal dinosaurs. Some of these were made by quite large creatures that must have had tree-trunk-like legs (Marty et al. 2013). The most likely candidates for these would have been advanced sauropodiforms or true sauropods, like Schleitheimia.

That has been it for today! Join me in the next post where we take a look at the Swiss dinosaurs of the Jurassic, Cretaceous… and Eocene! See you until then!

Related Posts:

• Gresslyosaurus: The Eldritch Dinosaur that turned its discoverer insane
• My Trip to the Dinosaur Museum of Frick
• Fossil Hunting in the Jura Mountains of Holderbank
• Visiting the Sauriermuseum Aathal - Part 3: More Exhibits
• My First Book: The Saurus Family and the Little Trilobite

References:

• Avanzini, Marco; Cavin, Lionel: A new Isochirotherium trackway from the Triassic of Vieux Emosson, SW Switzerland: stratigraphic implications, in: Swiss J. Geosci, 102, 2009, S. 353 – 361.
• Brinkmann, Winand: Paläontologisches Museum der Universität Zürich. Führer durch die Ausstellung, Zürich 1994.
• Butler, Richard; Porro, Laura; Heckert, Andrew: A supposed heterodontosaurid tooth from the Rhaetian of Switzerland and a reassessment of the European Late Triassic record of Ornithischia (Dinosauria), in: Neues Jahrbuch für Geologie und Paläontologie, 2006, 10, S. 613 – 633.
• Feldmann, Mark & Heinz, Otto: Die Saurierspuren am Tödi und ihre geologische Umgebung, in: Sommer der alpinen Artenvielfalt, 2008.
• Furrer, Heinz: Dinosaurier im Schweizerischen Nationalpark. Cratschla, in: Ediziuns specialas, 1, 1993, S. 4–24.
• Galton, Peter: Prosauropod dinosaur Plateosaurus (= Gresslyosaurus) (Saurischia; Sauropodomorpha) from the Upper Triassic of Switzerland, in: Palaeontol. Geol., 20, 1986, S. 167 – 183.
• Heer, Oswald: Die Urwelt der Schweiz, Zürich 1865 (&2. Ausgabe 1883).
• Martin, Anthony: Dinosaurs Without Bones. Dinosaur Lives Revealed by their trace fossils, New York 2014.
• Marty, Daniel; Meyer, Christian; Stecher, Rico; Thüring, Basil: Dinosaurierspuren aus der Trias der Bergüner Stöcke (Parc Ela, Kanton Graubünden, SE-Schweiz, in: Mitteilungen der Naturforschenden Gesellschaften beider Basel, 14, 2013.
• Meyer, Christian & Thüring, Basil: Dinosaurs of Switzerland, in: Comptes Rendus Paleovol, 2, 2003, S. 103 – 117.
• Meyer, Christian; Thüring, Basil; Wizevich, Michael: The Norian and Rhaetian dinosaur tracks of eastern Switzerland in the light of sequence stratigraphy, in: Swiss Geoscience Meeting 2015.
• Meyer, Christian; Klein, Hendrik; Wizevich, Michael; Stecher, Rico: Triassic Sauropodomorph tracks with Gondwanan affinities from the Central Austroalpine Nappes of Switzerland, in: Swiss Geoscience Meetin, 17, Fribourg 2019.
• Moser, M.: Plateosaurus engelhardti Meyer, 1837 (Dinosauria: Sauropodomorpha) aus dem Feuerletten (Mittelkeuper; Obertrias) von Bayern, in: Zitteliana B,24, 2003, S. 1–188.
• Mouchet, Phillipe: A new sauropods printsite from the Upper Jurassic of northern Switzerland Kimmeridgian; Montbautier, Kt Bern, in: Revue de Paleobiologie, 122, 1993, S. 345-349.
• Paul, Gregory Scott: Predatory Dinosaurs of the World. A Complete Illustrated Guide, New York 1988.
• Rauhut, Oliver; Holwerda, Femke; Furrer, Heinz: A derived sauropodiform dinosaur and other sauropodomorph material from the Late Triassic of Canton Schaffhausen, Switzerland, in: Swiss Journal of Geosciences, 113, 2020.
• Sander, Martin: The Norian Plateosaurus Bonebeds of central Europe and their taphonomy, in: Palaeogeophraphy, Palaeoclimatology, Palaeoecology, 93, 1992, S. 255 – 299.
• Schalch, Ferdinand & Peyer, Bernhard: Über ein neues Rhätvorkommen im Keuper des Donau-Rheinzuges, in: Mitteilungen der Badischen Geologischen Landesanstalt, 8, 1919, S. 263–298.
• Tatarinov LP: New data on a collection of tetrapod teeth from the Rhaetian of Hallau (Switzerland), in: Paleontological Journal 19, 1985, S. 138–140.
• Weems, Robert: Locomotor Speeds and Patterns of Running Behavior in Non-Maniraptoriform Theropod Dinosaurs, in: New Mexico Museum and Natural History and Science Bulletin, 37, 2006.
• Zahner, Marion & Brinkmann, Winand: A Triassic averostran-line theropod from Switzerland and the early evolution of dinosaurs, in: Nature ecology & evolution, 3, 2019, S. 1146 – 1152.
• Zahner, Marion: Osteology and Phylogenetic Relationships of the Upper Triassic Theropod Specimens of Frick, Aargau, Switzerland and the Significance of the Locality for a Better Understanding of the Evolution and Ecology of Early Dinosaurs, 2023 (Doctoral thesis for the University of Zürich).

 Image Sources:

• Fig. 2: Meyer & Thüring 2003.
• Fig. 7: Everything Dinosaur
• Fig. 9 – 11: Marty et al. 2013