2 articles · Updated · The Brighter Side of News · Aug 11
Summary
Tetonius varleyorum, a newly described 55-million-year-old primate from Wyoming’s Smiley Draw, shows a mix of primitive and advanced dental traits that disrupts a long-standing straight-line model of Tetonius evolution.
The key evidence lies in its teeth: the species lacks a second lower premolar and has an enlarged first lower incisor, yet retains a double-rooted third lower premolar, pointing to branching lineages and parallel evolution.
Nearly 1,000 tooth-bearing jaws and jaw fragments from Smiley Draw also revealed two rarely documented omomyids, making the site’s primate community notably different from Wyoming’s better-studied Bighorn Basin.
That contrast suggests geography, habitat and timing shaped early North American primates more strongly than models built mainly on the Bighorn Basin had implied, though Smiley Draw’s exact age still needs tighter dating.