As if hidden from the paleo tooth fairy, a lone molar belonging to a hoofed mammal stayed tucked beneath a pillow of volcanic rock in central India for more than 65 million years. Recently uncovered, the tooth predates similar fossils found across the globe.
The dental discovery sheds light on the evolution of adaptations that allowed a group of mammals called ungulates to thrive as expert grazers. It also suggests, according to newly published research on the tooth, that the Indian subcontinent could be the point of origin of many groups of mammals.
The lower right molar, about half the size of an ant (2.5 millimeters long), was found embedded in central India's Deccan volcanic flows. The researchers estimate the tooth dates back to the late Cretaceous period (144 million to 65 million years ago), a time when India was not connected with other continents and dinosaurs still walked the Earth.
The fossil belonged to a new species of ungulate dubbed Kharmerungulatum vanvaleni, a hoofed animal related to modern horses, cows, pigs, sheep and deer. And it represents the oldest known evidence for the so-called archaic ungulates (small, primitive hoofed mammals), predating by millions of years the explosion of mammalian life that occurred during Paleocene Epoch, from 65 million to nearly 55 million years ago.
"Until now, the known fossil record of [the] oldest archaic ungulates or supposed ancestors of living ungulates comes from the Early Paleocene of North America," Guntupalli Prasad of the University of Jammu in India told LiveScience. He is the lead author of the tooth study, detailed in the Nov. 9 issue of the journal Science.
So the ungulates survived on the Indian subcontinent throught he Deccan Traps to the current day. huh. Very, very deadly that eruption.
Something about this doesn't seem quite right to me.
ReplyDeleteFor one, genetic information shows ungulates are not a valid clade. # Perissodactyla and Cetartiodactyla fairly closely related, but the former is closer related to Carnivora. Then there's the now-known Afrotherian Ungulates (Hyraxes, Elephants, Sirenians, Aardvarks), the South American Ungulates which no one knows the roots of, and Condylarths and the like, which may be dead ends, primitive Laurasiatheria, or something even weirder, or some mix of the three.
Perhaps what the article meant is they found the ur-Cetartiodactyla, as all the hooved animals mentioned are even-toed. However, it seems like the fossil is in the wrong location. Laurasiatheria is called that because all the clades seem to have arisen in Laurasia.
From what I can see from the summary in science, the authors realize this is a revolutionary idea - as it means either we're dealing with a "rafting" species from Asia or this branch of hooved animals evolving in India.
Given genetics it looks worse than that however, as it implies an ultimate Gondwana origin for essentially all Placental clans. Which is possible, but means there should be ghost linages for dozens of closely-related groups in India, which somehow went extinct in Africa, Madagascar, South America, and Australia before later re-colonizing them in other ways.
It seems more likely that the tooth morphology is homologous to later "Ungulates," much as the same morphology evolved in several different clades of placental mammals. But, I'm just a paleo-geek layman, so what do I know?
Hey Karl,
ReplyDeleteSomething about this doesn't seem quite right to me.
Totally agreed.
Given genetics it looks worse than that however, as it implies an ultimate Gondwana origin for essentially all Placental clans. Which is possible, but means there should be ghost linages for dozens of closely-related groups in India, which somehow went extinct in Africa, Madagascar, South America, and Australia before later re-colonizing them in other ways.
There is a bit of evidence that the placentals might have been a Gondwana originating group: Dr Tom Rich of Australia found Cretaceous fossils of placentals. Or maybe everyone is seeing convergent evolution of different groups taht we are simply unaware of. *shrugs*
I am not an authority on any group's evolution, truthfully. What makes this find oh-so-interesting for me is that it happens to be SMACK in the middle of Gerta Keller's Deccan Traps that she believes are munching on the dinos. It is something that I disagree with, so this is just a another tidbit of evidence.
PS. Nice and informative comment, btw.