A new discovery might be about to give your Jurassic Park cane an upgrade, as the first-ever true crab from the age of dinosaurs has been found preserved in amber. The crustacean, named Cretapsara athanata, is around 100 million years old and yet remains in tip-top condition, with the anatomy of its gills still intact. Being in such good nick means the remarkable find brings with it some fascinating insights, potentially shining a light on how land crabs diverged from their earlier marine cousins.
The gills of a crab are very delicate and as such don’t get on well with millions of years of preservation. Despite this, the researchers on the new paper, published in the journal Science Advances, found C. athnata’s gills to be in remarkably good condition. Their structure indicates that in its time this crab enjoyed an amphibious or freshwater lifestyle, making it an evolutionary departure from its marine-dwelling ancestors.
This is exciting because it would demonstrate that true crabs already existed in freshwater habitats early on in the Late Cretaceous, far earlier than the previous estimates and in turn closing a gap in the sparse fossil record (in terms of bejeweled crabs) of around 50 million years.
“Cretapsara athanata, whose name means ‘the immortal Cretaceous spirit of clouds and waters’, seems to represent the oldest non-marine crab on record, bridging the gap between the predicted molecular time of split of non-marine crabs (~130 million years ago) and their much younger fossil record (~75–50 million years ago),” study author Dr Javier Luque told IFLScience. “It is also telling us that true crabs have conquered non-marine habitats independently over a dozen times since the mid-Cretaceous.”
A fancy crab indeed, it seems, so where did it come from? The shiny fossil in question was part of a batch of commercial “raw” amber pieces that were gathered by Burmese miners and sold to a gemstone vendor at a fair in 2015. Luckily, the rough diamond (figuratively speaking) was later polished at which point its true value was discovered. It was later acquired by the Longyin Amber Museum, Yunnan Province, China, where it now lives among the museum’s scientific collections.
Around 100 million years before it became committed to amber, it was lurking around in either brackish or freshwater near a coastal estuary, a poignant placement for a wee crab that may well be bridging a big gap between marine and non-marine crabs.
As for Luque and colleagues’ next steps, they’re keen to delve into the fascinating mechanisms behind carcinization: a bizarre evolutionary phenomenon through which so many things decided to turn into crabs.
“We want to delve deeper into why things keep evolving into crabs, to investigate their transitions from sea to land and freshwater, and their evolution and diversification over time leading to the modern forms seen today,” explained Luque. “For this, we are building the most complete family tree of life of crabs, as part of a National Science Foundation-funded project with a team of colleagues from Florida International University (Heather Bracken-Grissom) and Harvard University (Javier Ortega-Hernandez, Joanna Wolfe, and Javier Luque).”
Want to know what peak performance looks like? It requires at least 10 legs.