"Now we have the evidence from Cretaceous times [144 million to 66.4 million years ago] of live birth in ichthyosaurs," said Achim Reisdorf, a paleontologist at Switzerland's University of Basel who was not involved in the find.
All the bones belong to members of the same species, according to the scientists, and the specimens are so unique that they also constitute their own genus of ichthyosaur.
Ichthyosaurs were streamlined aquatic reptiles that breathed air and are believed to have subsisted mainly on squid.
One of their most prominent characteristics is their enormous eyes, the largest eyes ever found on any animal.
One specimen in Caldwell's study included the remnants of an eye, a notable find.
"The orbits [eye sockets] include space for pieces of bone that fit behind the eyeball and keep it from collapsing from the pressures of deep diving," Caldwell said.
"You need a huge eyeball to accumulate and concentrate the minimal light at 200, 300, 400 feet [60 to 120 meters] of depth."
The largest of the specimens is about 5 or 6 meters (16 to 20 feet) long, according to Caldwell, who notes that none of the specimens were fully grown adults. Ichthyosaurs ranged in size from 3 feet (about 1 meter) to more than 60 feet (18 meters).
In addition to the embryos and eye, the fossil find includes portions of a snout plus jawbones, skull bones, cheekbones, and teeth.
Maxwell and Caldwell named the new animals Maiaspondylus lindoei"maia" meaning "good mother" because the fossil was found along with embryos, and "spondylus" meaning "vertebra" because the embryos were found near the spinal column.
The species name, lindoei, is derived from the name of the man who first collected the specimens in 1971, Allan Lindoe.
Editor's Note: Michael Caldwell has received funding for research from the National Geographic Society.
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