Fossil Evidence Pushes Back Origin of Live Birth by 90 Million Years
Bone growth rings and a neonatal line suggest the fossil was born live, with a newborn-to-adult mass ratio of 14%, researchers said.
- A study published August 13 in Frontiers in Mammal Science reported that Chiniquodon theotonicus, a cynodont living 236 million years ago, gave birth to live young, pushing back viviparity's origin by up to 95 million years.
- Paleontologists long assumed cynodonts, the mammalian ancestors, reproduced by laying eggs; the C. theotonicus fossil discovered in northwestern Argentina challenges this view of Triassic-era reproduction.
- Lead author Dr. Leandro Gaetano identified a 'neonatal line' in fossilized bones showing the newborn weighed 1.7 kilograms, roughly 14% of its 12-kilogram adult mass—a ratio matching modern placental mammals.
- The findings suggest viviparity emerged 160 million years earlier than previously thought, providing what Anne Weil calls a "huge advantage" against predators during the Triassic's harsh climate.
- Eva Hoffman, a paleontologist at the American Museum of Natural History, cautioned that viviparity requires strong evidence and more fossilized embryonic tissues to confirm the team's proposed evolutionary scenarios.
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Fossil Evidence Pushes Back Origin of Live Birth by 90 Million Years
Paleontologists studying a 236-million-year-old cynodont fossil from Argentina say they have found the earliest evidence yet of viviparity (live birth) in the evolutionary line that leads to mammals, pushing back the origin of this reproductive strategy by as much as 90 to 95 million years. The post Fossil Evidence Pushes Back Origin of Live Birth by 90 Million Years appeared first on Sci.News: Breaking Science News.
Mammal ancestors may have given live birth 90 million years earlier than we thought, rewriting evolutionary timelines
A dog-sized carnivore and mammal ancestor that lived around 236 million years ago seems to have given birth to live young, a new study suggests. This means the tactic of keeping young developing inside the mother — known as viviparity — may have emerged in the mammalian lineage 90 million to 95 million years earlier than scientists previously thought, researchers noted in the study."This is the first time that we have evidence on how these m…
A 236-million-year-old fossil could rewrite the story of mammalian birth
Scientists may have uncovered evidence that a mammal ancestor was giving birth to live young 236 million years ago. A fossilized cynodont showed a neonatal growth line and an unusually large birth size that closely match patterns seen in modern mammals. The discovery could push the evolution of live birth back by up to 95 million years. It also raises the possibility that many supposedly “modern” mammalian traits evolved surprisingly early.
A 236-million-year-old fossil challenges the story of mammalian live birth
Some cynodonts may have been giving birth to live young much sooner in evolutionary history than previously assumed. A new Frontiers in Mammal Science study has offered the first compelling evidence that cynodonts may have been viviparous—a reproductive mode characterized by live birth.
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