A remarkably well-preserved skeleton of Mixodectes pungens presents insights into mammals’ evolutionary trajectory after non-avian dinosaur extinction.
For greater than 140 years, Mixodectes pungens, a species of small mammal that inhabited western North America within the early Paleocene, was a thriller. What little was identified about them had been principally gleaned from analyzing fossilized tooth and jawbone fragments.
However a brand new examine of essentially the most full skeleton of the species identified to exist has answered many questions on the enigmatic critter—first described in 1883 by famed paleontologist Edward Drinker Cope—offering a greater understanding of its anatomy, conduct, weight loss plan, and place within the Tree of Life.
The examine, coauthored by Yale anthropologist Eric Sargis, demonstrates that the mature grownup Mixodectes weighed about 3 kilos, dwelled in timber, and largely dined on leaves. It additionally reveals that these arboreal mammals—an extinct household often called mixodectids—and people occupy comparatively shut branches on the evolutionary tree.
“A 62-million-year-old skeleton of this high quality and completeness presents novel insights into mixodectids, together with a a lot clearer image of their evolutionary relationships,” says Sargis, professor of anthropology at Yale, curator of vertebrate paleontology and mammalogy at Yale Peabody Museum, and the director of the Yale Institute for Biospheric Research.
“Our findings present that they’re shut family of primates and colugos—flying lemurs native to Southeast Asia—making them pretty shut family of people.”
The skeleton was collected in New Mexico’s San Juan Basin by coauthor Thomas Williamson, curator of paleontology on the New Mexico Museum of Pure Historical past & Science, underneath a allow from the federal Bureau of Land Administration. It features a partial cranium with tooth, spinal column, rib cage, forelimbs, and hind limbs.
The researchers decided that the skeleton belonged to a mature grownup that weighed about 1.3 kilograms, or 2.9 kilos. The anatomy of the animal’s limbs and claws point out that it was arboreal and able to vertically clinging to tree trunks and branches. Its molar tooth had crests to interrupt down abrasive materials, suggesting it was omnivorous and primarily ate leaves, the examine reveals.
“This fossil skeleton supplies new proof regarding how placental mammals diversified ecologically following the extinction of the dinosaurs,” says Chester, a curatorial affiliate of vertebrate paleontology on the Yale Peabody Museum.
“Traits comparable to a bigger physique mass and an elevated reliance on leaves allowed Mixodectes to thrive in the identical timber seemingly shared with different early primate family.”
Mixodectes was fairly massive for a tree-dwelling mammal in North America in the course of the early Paleocene—the geological epoch that adopted the Cretaceous-Paleogene extinction occasion that killed off non-avian dinosaurs 66 million years in the past, the researchers word.
For instance, the Mixodectes skeleton is considerably bigger than a partial skeleton of Torrejonia wilsoni, a small arboreal mammal from an extinct group of primates referred to as plesiadapiforms, that was found alongside it. Whereas Mixodectes subsisted on leaves, Torrejonia’s weight loss plan principally consisted of fruit. These distinctions in measurement and weight loss plan counsel that mixodectids occupied a singular ecological area of interest within the early Paleocene that distinguished them from their tree-dwelling contemporaries, the researchers say.
Two phylogenetic analyses carried out to make clear the species’ evolutionary relationships confirmed that mixodectids had been euarchontans, a bunch of mammals that consists of treeshrews, primates, and colugos. Whereas one evaluation supported that they had been archaic primates, the opposite didn’t. Nonetheless, the latter evaluation verified that mixodectids are primatomorphans, a bunch inside Euarchonta composed of primates and colugos, however not treeshrews, Sargis explains.
“Whereas the examine doesn’t fully resolve the controversy over the place mixodectids belong on the evolutionary tree, it considerably narrows it,” he says.
The examine seems within the journal Scientific Stories.
Extra authors are from Brooklyn School, Metropolis College of New York; The Graduate Middle on the Metropolis College of New York; the College of Toronto Scarborough; and the Florida Museum of Pure Historical past on the College of Florida.
Supply: Yale
