April 5 (UPI) -- Scientists have identified the remains of six to eight tiny embryos inside the womb of a 180 million-year-old ichthyosaur specimen. The ancient reptile was pregnant with octuplets when she passed away.
The Early Jurassic ichthyosaur was found in 2011 in northeast England. It was owned by fossil collector Martin Rigby, who suspected the specimen housed a block of embryos. Dean Lomax, a paleontologist at the University of Manchester, confirmed Rigby's suspicion. Upon Lomax's recommendation, the Yorkshire Museum acquired the fossil for further analysis.
Ichthyosaurs were dolphin-like reptiles that gave birth to live young. They hunted and ate other small reptiles and fish.
Yorkshire's Jurassic strata have yielded hundreds of ichthyosaur fossils, but never ichthyosaur embryos. Of the handful of embryo-carrying ichthyosaur specimens found in Britain, the latest fossil is the youngest, hailing from the Toarcian stage of the Jurassic.
The fossil is contained within a small boulder. When paleontologists cut it in half, they found a few large rib bones and several vertebrate disks. They also found at least six tiny embryos, and probably eight.
"We also considered the possibility that the tiny remains could be stomach contents, although it seemed highly unlikely that an ichthyosaur would swallow six to eight aborted embryos or newborn ichthyosaurs at one time," Manchester researcher Mike Boyd said in a news release. "And this does not seem to have been the case, because the embryos display no erosion from stomach acids. Moreover, the embryos are not associated with any stomach contents commonly seen in Early Jurassic ichthyosaurs, such as the remains of squid-like belemnites."
Scientists aren't yet sure of the specimen's species, but the most common type of ichthyosaur found carrying embryos is Stenopterygius. More than 100 Stenopterygius ichthyosaurs have been found with embryos inside their wombs, several dozen in Germany.
"The German sites are approximately the same age as the new specimen from Whitby and it is possible that the new specimen is also Stenopterygius, but no identifiable features are preserved in the adult or embryos. Nonetheless, this is an important find," Dean said.
Researchers shared their analysis of the octuplet-carrying ichthyosaur in a new paper published this week in the journal Proceedings of the Yorkshire Geological Society.