Fossil Reclassified as New Genus of Early Crocodile Relative
The study, published in April 2026, details the identification of Eosphorosuchus lacrimosa from a specimen previously thought to be Hesperosuchus agilis.
A fossil discovered in 1948 at Ghost Ranch, New Mexico, has been reclassified as a new genus and species of early crocodile relative. The finding provides evidence of two distinct crocodylomorph species coexisting in the same environment during the Late Triassic period.
Discovery and Identification
The fossil was unearthed at Ghost Ranch in 1948. For approximately 75 years, it was stored in the collection of the Peabody Museum at Yale University, cataloged as a specimen of the known early crocodylomorph Hesperosuchus agilis.
A new analysis led by researchers, including Yale University paleontologist Miranda Margulis-Ohnuma, concluded the fossil represents a distinct genus and species, which they named Eosphorosuchus lacrimosa. The findings were formally published in the journal Proceedings of the Royal Society B: Biological Sciences in April 2026.
Fossil Description
The preserved specimen consists of:
- A skull
- Bones from one back leg
- One vertebra
- Three scales
Based on the remains, researchers estimate Eosphorosuchus lacrimosa was approximately the size of a large dog. The fossil was found in a geological formation dating to the Late Triassic period, between 237 million and 201 million years ago. One source specifies an age of approximately 205 million years.
Distinguishing Anatomical Features
The study identified several key features that differentiate E. lacrimosa from H. agilis:
- A shorter snout
- A thicker, more reinforced skull structure
- A larger, triangular postorbital bone in the skull
- Matching features on the lower jaw
The researchers state these anatomical traits suggest the creature had adaptations for a powerful bite.
Coexistence and Ecological Implications
A fossil of Hesperosuchus agilis was found approximately 5 meters (15 feet) away from the E. lacrimosa specimen within the same geological layer. The study authors state the animals lived at the same time and their remains were buried in a single event, which they suggest may have been a flood.
The researchers propose that the physical differences, particularly in snout shape and skull reinforcement, indicate the two species may have occupied different ecological niches.
They suggest shorter-snouted forms like E. lacrimosa could have fed on different types of prey compared to longer-snouted forms like H. agilis.
Research Context and Statements
In statements provided in the study, co-author Miranda Margulis-Ohnuma described the finding as evidence of coexistence between two "functionally different-looking crocodylomorphs" early in their evolutionary history.
She noted that the fossil record for early crocodylomorphs is limited, with many Triassic species known only from single specimens. Margulis-Ohnuma stated that new fossil discoveries continue to change the scientific understanding of this group's early evolution.