Reconstruction of Megaconus mammaliaformisUniversity of Chicago, April IschBetween ancient, fragmented specimens and convoluted phylogenetic analyses, early mammalian evolution has long been a topic of scientific debate. Now, two newly discovered Jurassic-era fossils seem to only complicate matters further, suggesting possible mammalian origins that differ by tens of millions of years.
The fossils, presented today (August 7) in Nature, were excavated by two teams working independently in China. Both specimens are nearly complete skeletons of haramiyids—early mammal-like creatures noted for their jaws and teeth—and estimated to be more than 160 million years old. Though the skeletal artifacts suggest the animals may have been relatives, their skeletons show markedly different features.
“Mammalian phylogeny is complex,” said Guillermo Rougier, a professor of anatomical sciences and neurobiology at the University of Louisville, who was not involved in either study. “The events we are trying to resolve occurred in the distant past—pertinent fossils are generally small, difficult to find, and often woefully incomplete.”
However, he added, “the two skeletons just described are precisely the high-quality specimens that allow scientists to ...
