Embryo-carrying eggs preserved within an ancient arthropod fossil. Photo by Royal Ontario Museum
TORONTO, Dec. 17 (UPI) -- Scientists have been finding and studying Waptia fieldensis, an extinct shrimp-like arthropod species, for more than a century, but only recently did researchers realize the creatures practiced brood care.
Researchers at the University of Toronto discovered a 508-million-year-old Waptia fossil with embryo-carrying eggs preserved within the body. It's the oldest evidence of brood care yet uncovered.
The fossil is one of several found with preserved eggs -- all detailed in a new scientific paper published in the journal Current Biology.
Waptia fieldensis were first discovered over 100 years ago in Canada's Middle Cambrian Burgess Shale, a renowned fossil deposit.
"As the oldest direct evidence of a creature caring for its offspring, the discovery adds another piece to our understanding of brood care practices during the Cambrian Explosion, a period of rapid evolutionary development when most major animal groups appear in the fossil record," said study author Jean-Bernard Caron, a professor of Earth sciences at Toronto and curator of invertebrate palaeontology at the Royal Ontario Museum.
The creature has a two-part shell structure covering the front section of its body-- a compact assemblage of abdomen, head and appendages -- known as a bivalved carapace. It appears to be uniquely designed for brood care.
"Clusters of egg-shaped objects are evident in five of the many specimens we observed, all located on the underside of the carapace and alongside the anterior third of the body," said Caron.
The eggs vary is their spacing from individual to individual, but all clusters exist in a single layer with little to no overlap.
"This creature is expanding our perspective on the diversification of brood care in early arthropods," said study co-author Jean Vannier, a paleontologist at the French National Center for Scientific Research in Lyon, France.
"The relatively large size of the eggs and the small number of them, contrasts with the high number of small eggs found previously in another bivalved arthropod known as Kunmingella douvillei," Vannier said. "And though that creature predates Waptia by about seven million years, none of its eggs contained embryos."