For over a century, scientists believed a single ichthyosaur species characterized the marine life preserved in the Plattenkalk limestone of southern Germany. This view has now been overturned. Researchers have uncovered a second species, Jabalisaurus tethyensis, previously misidentified within museum collections. Intriguingly, its closest kin are found nearly 9,000 kilometers away in Mexico.
The Plattenkalk layers are renowned fossil deposits famous for yielding Archaeopteryx, a fossil pivotal to understanding the dinosaur-to-bird transition. Until recently, scientists thought only Aegirosaurus leptospondylus represented ichthyosaurs from these Late Jurassic strata in southern Germany.
This one-species model shaped broader interpretations of ichthyosaur diversity during the Late Jurassic, suggesting these marine reptiles were less varied than in earlier periods.
A Hidden Species Revealed in Museum Collections
The team, led by Dr. Erin Maxwell from the Staatliches Museum für Naturkunde Stuttgart, did not discover new fossils in the field. Instead, they reexamined existing specimens previously labeled as Aegirosaurus and recognized a distinct new species.
The key fossil is a juvenile skeleton housed at the Bavarian State Collection for Palaeontology and Geology in Munich, originally retrieved from the Geisberg quarry near Apfelthal, Bavaria. The researchers also reassigned two other fossils to this new species: one held by the Staatliches Museum für Naturkunde Stuttgart and another from the Jura-Museum Eichstätt, which preserves a detailed soft-tissue imprint.
Jabalisaurus tethyensis was a medium-sized ophthalmosaurian ichthyosaur, measuring between 2 to 2.9 meters (6.6 to 9.5 feet) long. According to the study published in Palaeontologia Electronica, it featured a narrow, tall skull with finely ridged teeth, implying a diet primarily of small bony fish. The skin was likely smooth, consistent with other ichthyosaurs of this lineage. This creature thrived approximately 150 million years ago in the warm seas of the Tethys Ocean during the Late Jurassic.
Greater Jurassic Ichthyosaur Diversity Comes to Light
Dr. Maxwell and her team situate Jabalisaurus tethyensis within the extensive evolutionary lineage of ichthyosaurs, a group that first appeared in the Early Triassic and lasted until the early Late Cretaceous.
Throughout the initial 8.7 million years, ichthyosaurs reached peak diversity and exhibited significant anatomical variation as they adapted to various marine niches and feeding strategies.
“By the Jurassic, and especially by the end of the Aalenian (early Middle Jurassic), ichthyosaurs occupied a reduced range of ecomorphotypes, and historically were viewed as being correspondingly reduced in taxonomic diversity,” explained the authors.
The identification of Jabalisaurus tethyensis doubles the known ichthyosaur species count in Germany’s Plattenkalk limestone, revealing a richer marine ecosystem than previously acknowledged. Many species had gone undetected due to their initial misclassification within collections.
A Genus Unveils Ancient Marine Connections Across Continents
One of the most striking findings is not just the species discovery but the biogeographical implications. Jabalisaurus was until now known only from fossils found near the Gulf of Mexico. Its presence in Bavaria suggests this marine reptile inhabited an extensive range across the ancient Tethys Ocean and associated proto-Caribbean waters.
The researchers identified closely related species pairs located in these disparate regions: Jabalisaurus meztli and Jabalisaurus tethyensis, alongside Parrassaurus yacahuitztli and Aegirosaurus leptospondylus.
“Despite the apparent high Late Jurassic marine habitat connectivity, the Late Jurassic ichthyosaurian fauna from the proto-Gulf of Mexico has been interpreted as being highly endemic,” noted the paper.
This research suggests these ichthyosaurs inhabited a wide range stretching from the northwestern Tethys to the proto-Caribbean Sea, with regional populations evolving into distinct species while remaining part of a shared warm-water and tropical fauna.
In contrast, ichthyosaurs found in cooler zones, such as the United Kingdom, Svalbard, Eastern Europe, and Argentina, belonged to more temperate to polar ecological communities.
- Categories:
- Science
0 comments
Sign in to Comment