Topic
The evolutionary history of mammals, tracing anatomical traits like teeth, lactation, and reproduction from early reptile-mammal ancestors to modern species.
Megacauda sungei, a mammaliaform from Jurassic China, pushes the bony anatomy of mammal suckling back to nearly 165 million years ago, a Nature study reports. The structures place the groundwork for a defining mammal trait well before the first modern mammals.
Reality
Dongoconodon platycauda, a 120-million-year-old swimming mammal from Liaoning, was forming a third generation of teeth, a Nature Communications study reports. The single skeleton cuts against the old assumption that two sets of teeth arose early in mammals, though it cannot show where that pattern began.
Reality
Researchers describing Megacauda sungei in Nature say the half-metre Jurassic swimmer had a throat built for suckling 165 million years ago. That puts the anatomy for milk-feeding earlier than the last common ancestor of all living mammals.
Perspective Coverage
5 publishersReality
Dongoconodon platycauda, a 120-million-year-old swimming mammal from Liaoning, replaced all four tooth classes repeatedly, its describers report. Bristol's Mike Benton accepts the teeth but calls them a late retention, so the fossil may tell us more about one lineage than about where mammals came from.
Reality
Researchers describing Tamirkhan balcarceli in Nature place zhelestids, long argued to be early placental relatives, among shrew-like zalambdalestoids. The Gobi skeleton suggests teeth alone misled the group's classification for nearly 40 years.
Reality
Zoos have bred short-beaked echidnas before, but repeated attempts at a dedicated research colony failed. Oliver Griffith's group at Macquarie has now reared a pouch baby, which is the precondition for sampling monotreme reproduction on a schedule.
Reality