Description and Classification

Notatesseraeraptor was a relatively small, bipedal carnivore, estimated to be around 3 meters (approximately 10 feet) in length. Like other early theropods, it would have had a slender build, a long tail for balance, and sharp, recurved teeth for hunting. Its hands likely possessed grasping capabilities, useful for catching small prey.

The classification of Notatesseraeraptor is particularly interesting due to its “mosaic” of characteristics. It is considered a neotheropod, a group that includes most theropod dinosaurs. However, it sits in a crucial position near the base of the neotheropod family tree. While displaying some features similar to coelophysoids like Coelophysis, and others reminiscent of dilophosaurids such as Dilophosaurus, Notatesseraeraptor also possesses traits that align it more closely with Averostra, the group containing most later theropods, including ceratosaurs and tetanurans (which include giants like Allosaurus and birds). The original describers placed Notatesseraeraptor as a non-averostran neotheropod that is the sister taxon to Averostra, meaning it is considered very closely related to the common ancestor of all averostran dinosaurs. This makes it more derived than typical coelophysoids or dilophosaurids.

Distinguishing Features

Notatesseraeraptor is set apart by a unique combination of primitive and advanced anatomical traits. These include:

• A skull roof that shows a mix of features, some seen in basal neotheropods and others more typical of averostrans.
• The presence of pneumatic openings (air sacs invading the bone) in its cervical (neck) vertebrae. While some earlier theropods show limited pneumatization, the extent in Notatesseraeraptor is more comparable to that seen in Dilophosaurus and more advanced theropods.
• The astragalus and calcaneum (ankle bones) are fused to the tibia, forming a tibiotarsus, a characteristic feature of neotheropods.
• The ilium (the largest hip bone) has a distinct shape and features that combine characteristics seen in different early theropod groups.
• Overall, its anatomy presents a “mosaic,” making it a key transitional fossil for understanding early theropod evolution.

Paleoenvironment and Diet

The fossils of Notatesseraeraptor were discovered in the Klettgau Formation of northern Switzerland. During the Late Triassic, this region was part of the supercontinent Pangaea and experienced a warm climate with distinct wet and dry seasons. The environment was likely a floodplain with river systems and vegetated areas. Notatesseraeraptor shared this environment with a variety of other animals, including large prosauropod dinosaurs like Plateosaurus, crocodile-like phytosaurs, armored aetosaurs, early turtles, amphibians, and various small reptiles and mammal relatives.

As a theropod, Notatesseraeraptor was a carnivore. Given its size, it probably hunted small vertebrates such as lizards, early mammals, and perhaps the young of other dinosaurs. Its sharp teeth and agile build would have made it an effective predator in its ecosystem.

Significance and Ongoing Research

The discovery of Notatesseraeraptor is highly significant for several reasons. It provides a rare glimpse into theropod diversity in Europe during the Late Triassic, a critical period for dinosaur evolution. Its unique combination of anatomical features offers important clues about the evolutionary steps leading from early neotheropods to the major radiation of Averostra, which dominated terrestrial ecosystems for the rest of the Mesozoic Era.

Ongoing research on Notatesseraeraptor may involve more detailed analysis of its skeletal anatomy to further refine its exact position within the theropod family tree. Comparisons with new fossil discoveries from the Triassic and Early Jurassic periods worldwide will help to build a more complete picture of early dinosaur evolution and biogeography. The study of Notatesseraeraptor helps paleontologists understand how different theropod lineages acquired the traits that led to their later success.