236-Million-Year-Old Chiniquodon Pushes Live Birth Back by 95 Million Years
Updated
Updated · Frontiers · Aug 13
236-Million-Year-Old Chiniquodon Pushes Live Birth Back by 95 Million Years
3 articles · Updated · Frontiers · Aug 13
Summary
A new study concluded Chiniquodon theotonicus gave live birth, making it the earliest known mammalian-lineage ancestor with evidence of viviparity.
Researchers based that finding on a rarely preserved neonatal line in the fossil and on body-mass comparisons with thousands of living mammals, reptiles and birds.
The team estimated the animal weighed about 1.7 kg at birth and 12 kg at death, a 14% newborn-to-adult ratio that aligns with placental mammals rather than egg-laying amniotes.
Because Chiniquodon lived about 236 million years ago, the result pushes the origin of mammalian viviparity back by roughly 90 to 95 million years and suggests other cynodonts may also have borne live young.