Aug 14, 2026 05:45 PM
https://www.frontiersin.org/news/2026/08...lian-birth
INTRO: For many years, cynodonts - animals that were a transitional link between early synapsids, a group of animals among which true mammals evolved, and the first true mammals - were believed to have laid eggs. Now, for the first time, a new study has found evidence to the contrary. Using a neonatal line, which is only rarely conserved in the fossil record, and comparisons of newborn-adult body weight ratios, a team in Argentina concluded that Chiniquodon theotonicus gave birth to live young. This pushes the timeline of this evolutionary adaptation back by up to 95 million years, said the team, and offers new avenues to reconstruct ecological aspects of the Triassic world.
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.
“We show for the first time that live birth was present in at least one mammalian ancestor, Chiniquodon theotonicus, which lived approximately 236 million years ago,” said lead author Dr Leandro Gaetano, a paleontologist at the National Scientific and Technical Research Council (CONICET) in Argentina. “This implies that viviparity among early cynodonts originated in the mammalian lineage at least 95 to 90 million years earlier than previously thought.” (MORE - details)
INTRO: For many years, cynodonts - animals that were a transitional link between early synapsids, a group of animals among which true mammals evolved, and the first true mammals - were believed to have laid eggs. Now, for the first time, a new study has found evidence to the contrary. Using a neonatal line, which is only rarely conserved in the fossil record, and comparisons of newborn-adult body weight ratios, a team in Argentina concluded that Chiniquodon theotonicus gave birth to live young. This pushes the timeline of this evolutionary adaptation back by up to 95 million years, said the team, and offers new avenues to reconstruct ecological aspects of the Triassic world.
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.
“We show for the first time that live birth was present in at least one mammalian ancestor, Chiniquodon theotonicus, which lived approximately 236 million years ago,” said lead author Dr Leandro Gaetano, a paleontologist at the National Scientific and Technical Research Council (CONICET) in Argentina. “This implies that viviparity among early cynodonts originated in the mammalian lineage at least 95 to 90 million years earlier than previously thought.” (MORE - details)
