Bipedal "Witch Croc" Fossil Rewrites Reptile Evolutionary History

Paleontologists in northern New Mexico have unearthed the fossilized remains of a remarkable reptile that walked on two legs and possessed a beak-like mouth, bearing a striking resemblance to small dinosaurs. However, this creature, named Labrujasuchus expectatus, lived approximately 212 million years ago, predating the evolution of dinosaurs with similar traits by over a hundred million years. The surprising discovery reveals that this ancient animal was not a dinosaur, but an early relative of crocodiles, showcasing the diverse evolutionary experiments occurring during the Late Triassic period.

The finding, formally described in the spring of 2026 by a team led by the Natural History Museum of Los Angeles County, places Labrujasuchus within the Shuvosauridae family, a group of bipedal, small-armed archosaurs known for their distinctive beaks. These creatures roamed the southern United States between 235 and 201 million years ago. Researchers note that their overall silhouette closely mimicked that of Cretaceous dinosaurs like ornithomimosaurs, often compared to modern ostriches. This striking similarity is a prime example of convergent evolution, where unrelated lineages independently develop similar physical characteristics in response to similar environmental pressures.

Evolutionary Convergence in the Triassic

The significance of Labrujasuchus expectatus lies in the timing of these evolutionary developments. While the crocodile lineage achieved this bipedal, beaked form during the Triassic, the dinosaur lineage that would eventually produce ornithomimosaurs did not develop comparable features until the Cretaceous period. "Bipedalism is a path well-trodden by dinosaurs and later birds, but a unique route for crocodile relatives to take," stated Alan Turner, lead author of the study and professor of anatomical sciences at Stony Brook University. "It worked for these creatures, which is why the same template kept reappearing across the next two hundred million years of vertebrate history." The creature itself was modestly sized, lacking the conical teeth characteristic of modern crocodiles.

The Late Triassic world was a period of immense evolutionary innovation. Dinosaurs were only beginning their ascent, remaining relatively minor players in the terrestrial ecosystem. The dominant reptiles at the time were the ancient crocodile relatives, which were exploring a wide array of forms far removed from their modern descendants. The fossil site in New Mexico, known as the Hayden Quarry at Ghost Ranch, has yielded exceptionally preserved fossils for nearly a century. This location, famously captured in the art of Georgia O'Keeffe, has been the focus of a collaboration between the Natural History Museum of Los Angeles County and Ghost Ranch since 2006.

The discovery of Labrujasuchus adds a crucial piece to the puzzle of shuvosaur evolution. "The team had reasonable confidence, given the temporal gap and the morphological pattern, that an intermediate form was probably waiting to be described," explained Nate Smith, co-author and director of the Dinosaur Institute at NHMLAC. The species name, expectatus, directly translates to "expected," reflecting the paleontologists' anticipation of such a find to bridge an evolutionary gap between known species.

Beyond the fascinating anatomy of the creature itself, Labrujasuchus offers profound insights into the mechanisms of evolution. It challenges the conventional notion that evolutionary forms arise once and then diversify. Instead, the Triassic fossil record repeatedly demonstrates that similar biological solutions can emerge independently across vastly different branches of the evolutionary tree. The beaked, bipedal, small-armed silhouette, for instance, was independently adopted by Triassic crocodile cousins, Cretaceous theropod dinosaurs, and modern birds. This suggests that there may be a limited number of optimal forms for certain ecological niches, leading distant lineages to converge on the same successful designs over vast spans of geologic time. Labrujasuchus is a compelling testament to this evolutionary principle, proving that the history of life is far more complex and surprising than often depicted.