Oldest Alligator Ancestor Identified in Colorado — SkimNews
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- Mandrasuchus milleri, a newly identified 2-metre crocodilian from Colorado's Corral Bluffs site, is the oldest known member of the alligator subfamily, with its oldest skulls dating to roughly 350,000 years after the asteroid strike that ended the Cretaceous Period 66 million years ago.
- Sadie Sherman and a Denver Museum of Nature & Science team recovered bones from about 15 individuals plus hundreds of teeth, bony skin plates (osteoderms) and other fossils, suggesting the species was abundant in the extinction's aftermath.
- The crocodilian combined pointed front teeth for seizing prey with bulbous, molar-like back teeth for crushing shellfish and hard-bodied prey — a flexible, omnivorous diet Sherman linked to its survival in a devastated ecosystem.
- Researchers compared 330 anatomical features against nearly 150 living and extinct crocodilians before classifying the fossils as an alligatorine, the subfamily that includes today's American and Chinese alligators.
- Several Mandrasuchus skeletons were found with bones still connected, including one inside what may have been a burrow — a behavior Sherman said could have sheltered the animals from harsh post-asteroid conditions.
- Independent experts Adam Cossette (New York Institute of Technology) and Pedro Godoy (University of São Paulo) called the fossils "compelling" and "beautifully preserved," saying they clarify how alligatorids diversified almost immediately after the end-Cretaceous extinction.
- The name blends the Greek "mandra" (enclosed space, for Corral Bluffs) with "Suchus" — the Greek name for the crocodile-headed Egyptian god Sobek — while "milleri" honors former Denver Museum researcher Ian Miller, who found many of the specimens.
Why it matters: Before this find, the timeline of how alligatorids branched from other crocodilians and then split into today's alligators and caimans was poorly resolved. With the oldest known alligatorine now anchored to roughly 350,000 years post-impact, paleontologists have a concrete reference point for tracing how large-bodied apex predators reassembled in the extinction's wake.
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