Ancient Cynodont Fossil Pushes Live Birth Deep into Mammal Lineage

TL;DR
Analysis of a 236-million-year-old cynodont fossil from Argentina reveals a neonatal bone line indicating live birth, with a newborn mass around 1.68 kg (about 10–20% of an adult), suggesting viviparity originated in the mammalian lineage far earlier than thought (roughly 90–95 million years ago) and proposing two plausible evolutionary scenarios for this trait's emergence.
- Fossil Evidence Pushes Back Origin of Live Birth by 90 Million Years Sci.News
- These mammal ancestors birthed live young far earlier than thought sciencenews.org
- A 236-million-year-old fossil challenges the story of mammalian live birth Phys.org
- Ancient Fossil Changes the History of Live Birth Newser
- This 236-Million-Year-Old Fossil Just Rewrote the Story of Live Birth Gizmodo
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