Scientists have described a new species of Jurassic ichthyosaur from southern Germany. The new species named Jabalisaurus tethyensis, lived around 149 million years ago during the Late Jurassic (Tithonian faunal stage). Remarkably, some fossils assigned to Jabalisaurus tethyensis had previously been classified as Aegirosaurus. The research highlights the hidden diversity of ichthyosaurs in the famous German Plattenkalk deposits.
The scientific paper (open access) has been published in the journal “Palaeontologia Electronica”.
A life reconstruction of a Late Jurassic ophthalmosaurian ichthyosaur. Note the presence of a rhamphorhynchid pterosaur in the distance. Picture credit: Everything Dinosaur.
Picture credit: Everything Dinosaur
A Revision of Late Jurassic Ichthyosaurs
Ichthyosaurs were highly specialised, superbly adapted marine reptiles. They first appeared during the Early Triassic and survived into the early Late Cretaceous. It had been thought that ichthyosaur diversity was greatest during the first ten million years of their evolution. Such diversity was initiated by radiation to diverse marine habitats and the development of a range of dietary niches. However, in contrast to this view, there has been an increasingly amount of evidence presented indicating the Tithonian as another high point in ichthyosaur diversity.
Southern Germany has produced many spectacular Late Jurassic fossils. These include fishes, turtles, marine reptiles, dinosaurs and early birds such as Archaeopteryx. However, ichthyosaur fossils are relatively rare.
Ichthyosaur fossils from the Bavarian Plattenkalk deposits of southern Germany were first described during the 1850s. Numerous taxa were erected. Unfortunately, none of the original fossil material is still available for study. Hence, only a single genus has been documented from these rocks – Aegirosaurus leptospondylus. In addition, the number of ichthyosaurs assigned to the Ophthalmosauridae family has dramatically increased. There are now more than twenty genera of ophthalmosaurian ichthyosaurs known. As a result of the increased data set, fossils previously assigned to the ophthalmosaur A. leptospondylus under phylogenetic analysis no longer match these new score characteristics. Therefore, the authors of this study re-assign most of the referred A. leptospondylus material to a new species in the Jabalisaurus genus (Jabalisaurus tethyensis).
The researchers conclude that there are at least two ichthyosaur genera present in these German deposits.
Introducing Jabalisaurus tethyensis
Jabalisaurus tethyensis was a medium-sized ophthalmosaurian ichthyosaur. Members of the genus are estimated to have reached between two and just over three metres in length. The German species probably reached around 2–2.9 metres long. It had a slender skull, large eyes and numerous finely ridged teeth. These adaptations indicate that it probably hunted relatively small prey. The species name tethyensis refers to its distribution along the northern shelf of the ancient Tethys Ocean.
The holotype is specimen SNSB-BSPG 1954 I 608. It represents a small, immature animal from the Altmühltal Formation of Bavaria. This specimen had previously been assigned to Aegirosaurus leptospondylus. However, the new analysis revealed important anatomical differences. Consequently, the researchers removed several fossils from Aegirosaurus and reassigned them to Jabalisaurus tethyensis.
A Familiar Fossil Gets a New Identity
One of the referred specimens is particularly significant. Specimen number JME-SOS-08369 is an articulated ichthyosaur measuring approximately 1.84 metres long. It comes from the Lower Tithonian deposits of Blumenberg, near Eichstätt in Bavaria. Furthermore, the specimen preserves an extraordinary soft-tissue outline.
Everything Dinosaur previously wrote about this fossil in 2022. At the time, researchers referred JME-SOS-08369 to Aegirosaurus sp. The earlier study examined the exceptional soft-tissue preservation associated with this specimen. It also investigated a separate ichthyosaur tail from the Solnhofen deposits.
Scientists identified a yellowish amorphous substance associated with the fossils. Their analyses suggested that this material represented adipocere. Adipocere can form from fatty tissues during decomposition. Therefore, the researchers proposed that these ichthyosaurs possessed a layer of insulating blubber.
To read Everything Dinosaur’s article about this research: Ichthyosaurs Had Blubber According to New Research.
JME-SOS-08369 has now provided scientists with further information. Its anatomy helped the researchers reassess the diversity of Late Jurassic German ichthyosaurs. The fossil also preserves a remarkably complete body outline. The researchers describe this exceptional preservation as essentially “mummified”.
A line drawing of the preserved skull of Jabalisaurus tethyensis (specimen number JME-SOS-08369). Picture credit: Delsett et al with additional notation by Everything Dinosaur.
Picture credit: Delsett et al with additional annotation by Everything Dinosaur.
What Did Jabalisaurus tethyensis Eat?
The new research also provides information about the animal’s ecology. Its slender jaws and teeth suggest Jabalisaurus tethyensis (pronounced Hah-bal-ee-sore-us teh-fie-en-sis), was probably a pursuit predator. It likely hunted small bony fishes in the tropical waters surrounding the Late Jurassic islands of southern Germany. At that time, this region consisted of shallow tropical seas dotted with islands, reefs and protected lagoons. Fine carbonate sediments accumulated in relatively quiet inter-reef basins.
These conditions created the exceptional fossil deposits for which southern Germany is famous today.
The Germany/Mexico Connection
The identification of Jabalisaurus in Germany has wider palaeobiogeographical implications. Until this study, the Jabalisaurus genus was known only from Mexico. Jabalisaurus meztli was described in 2021 from Late Jurassic deposits associated with the ancient Gulf of Mexico (Barrientos-Lara and Alvarado-Ortega).
Finding a closely related species in Germany substantially extends the known geographical range of the genus. Furthermore, this discovery challenges the idea that Late Jurassic ichthyosaurs from the proto-Caribbean were strongly endemic. Instead, similar ichthyosaurs may have inhabited warm waters extending across the Tethys and into the proto-Caribbean.
The researchers propose the existence of a distinctive Peri-Tethyan ichthyosaur fauna. This fauna differed from ichthyosaurs living in more temperate and polar waters. Therefore, climate rather than geographical isolation may have strongly influenced Late Jurassic ichthyosaur distribution.
Museum Fossils Continue to Reveal Secrets
The description of Jabalisaurus tethyensis also demonstrates the importance of re-examining museum specimens. Some fossils included in the study have been known for decades. Nevertheless, new comparisons and modern phylogenetic analyses have changed their interpretation. The discovery effectively doubles the recognised ichthyosaur generic diversity of the German Plattenkalk deposits.
Furthermore, JME-SOS-08369 has now contributed to two important areas of ichthyosaur research. First, its exceptional preservation provided evidence concerning ichthyosaur soft tissues. Now, its anatomy has helped scientists recognise a previously overlooked species. The fossil record does not always require new fossils to produce new discoveries. Sometimes, important discoveries are already sitting in museum collections waiting to be re-examined.
The scientific paper: “Late Jurassic ichthyosaurs from southern Germany” by Erin E. Maxwell, Jule Neumann and Giovanni Serafini published in Palaeontologia Electronica.
For models of ichthyosaurs and other prehistoric animals: Marine Reptiles and Other Prehistoric Animal Models.
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