A new study published states that an ichthyosaur fossil may show the earliest form of live birth.
Ryosuke Motani and his colleagues from the University of California, Davis, reported a new fossil specimen, which belongs to Chaohusaurus (Reptilia, Ichthyopterygia), the oldest of Mesozoic marine reptiles that lived approximately 248 million years ago, reports Yahoo News.
Ichthyosaurs were giant marine reptiles that evolved from land reptiles and moved to the water. The partial skeleton was recovered in China, according to Science Daily. The maternal skeleton was found with two embryos and a neonate. Of the three offspring, one was born, one was still inside the mother, and one was in mid-birth. The headfirst birth position of the second embryo indicates that ichthyosaurs may have given live birth on land, instead of in the water as previous studies had thought. Being born headfirst is unusual, given that the majority of marine live births are tail first. Prior studies have revealed that live births were common in marine reptiles that could not lay eggs at sea or walk on land, but scientists have debated where this form of reproduction had originated.
"Being reptiles, their ancestors lived on land. What happened during the transition from land to the sea is not well understood, and Chaohusaurus holds a key to [unlock] the mystery," said Dr Ryosuke Motani from the University of California, Davis, US who undertook the study.
The fossil is the earliest of its kind, andon of only two records of Ichthyosaurs giving birth, reveals BBC Nature.
The full finding were published, and can be found in the journal PLoS One.