Description and Classification

Orthogoniosaurus is known from very incomplete remains, making its exact appearance and size difficult to determine with certainty. Based on the nature of its tooth, it is classified as a theropod dinosaur, a group of mostly carnivorous, bipedal dinosaurs that includes famous predators like Tyrannosaurus rex and Velociraptor. The original tooth described was somewhat straight and compressed from side to side, different from the more curved teeth of many other theropods.

The classification of Orthogoniosaurus has been a subject of debate among scientists. Due to the fragmentary nature of its fossils (just teeth), many paleontologists consider it a nomen dubium, which means “doubtful name.” This means the available fossils are not distinct enough to confidently identify it as a unique genus or to determine its precise relationships to other dinosaurs. It has sometimes been suggested to be related to abelisaurids, a group of theropods common in the ancient southern supercontinent Gondwana, which included India during the Cretaceous. Other theropods from the Lameta Formation, like Indosuchus and Rajasaurus, are abelisaurids. However, without more complete fossils, its exact place within the theropod family tree remains uncertain.

Distinguishing Features

Since Orthogoniosaurus is primarily known from its teeth, its recognized features are based on dental characteristics. These features are what likely led to its name:

• The teeth are described as being relatively straight compared to the more noticeably curved teeth of many other theropod dinosaurs.
• The teeth are flattened or compressed from side to side (laterally compressed).
• Fine serrations, like tiny steak-knife edges, are present on the cutting edges of the teeth, typical for carnivorous dinosaurs.

It is important to note that these features, while described for the original tooth, are not always unique enough to distinguish Orthogoniosaurus clearly from other theropods known only from teeth, contributing to its status as a doubtful name.

Paleoenvironment and Diet

Orthogoniosaurus lived in what is now India, in an environment preserved in the Lameta Formation. During the Late Cretaceous, this region was part of the ancient supercontinent Gondwana, though India was drifting northwards. The Lameta Formation represents a terrestrial environment characterized by rivers, floodplains, and lakes, under a semi-arid climate. This period was also marked by significant volcanic activity known as the Deccan Traps, which would have influenced the landscape and ecosystems.

As a theropod dinosaur, Orthogoniosaurus was a carnivore. Its teeth, with their sharp edges and serrations, were adapted for eating meat. It likely hunted or scavenged other animals living in its habitat. Potential prey could have included young titanosaurian sauropods like Isisaurus or Jainosaurus, which were abundant in the area, as well as smaller dinosaurs and other vertebrates.

Significance and Ongoing Research

Orthogoniosaurus is one of several dinosaurs named from the Lameta Formation, adding to our knowledge of the diverse fauna that inhabited India during the final stages of the dinosaur era. Even though its remains are scant, it represents part of the theropod dinosaur community in this region. The study of such fragmentary fossils highlights the challenges paleontologists face when reconstructing ancient ecosystems.

Due to its status as a nomen dubium, there is limited direct research focused solely on Orthogoniosaurus. The primary challenge is the lack of definitive fossil material. Future paleontological work in the Lameta Formation is crucial. The discovery of more complete theropod skeletons could help clarify the identity of animals currently known only from teeth, like Orthogoniosaurus, and potentially validate (or invalidate) the genus. Such finds would also improve our understanding of the relationships between Indian dinosaurs and those from other parts of Gondwana, like Madagascar, South America, and Africa, with which India shared connections before its northward drift.