A team of researchers has discovered the unexpected birthing habit of a massive sea lizard from the Cretaceous Period.
Publishing their work in the journal Paleontology, the scientists found the mosasaurs to have given birth to live offspring in the ocean rather than on land or even close to shore. Mosasaurs were one of the ocean's dominant predators and could grow to an imposing 50 feet in length.
"Mosasaurs are among the best-studied groups of Mesozoic vertebrate animals, but evidence regarding how they were born and what baby mosasaur ecology was like has historically been elusive," study lead author Daniel Field, a doctoral candidate in Yale University's Department of Geology and Geophysics, said in a news release.
For their study, the researchers were able to analyze the youngest mosasaur specimen uncovered to date, which Field first noticed in the Peabody Museum's stores.
"These specimens were collected over 100 years ago," he said. "They had previously been thought to belong to ancient marine birds."
Aaron LeBlanc, a doctoral candidate at the University of Toronto, co-authored the study with Field and two other members of Yale's geology and geophysics department, Adam Behlke and Adrien Gau. The fossils were originally discovered in open ocean deposits and were identified as mosasaurs thanks to distinct teeth and jawbones.
"Really, the only bird-like feature of the specimens is their small size," LeBlanc said in the release. "Contrary to classic theories, these findings suggest that mosasaurs did not lay eggs on beaches and that newborn mosasaurs likely did not live in sheltered near-shore nurseries."
