World's largest fossilized crab claw discovered dating back 8 million years
An 8.8 million-year-old fossil of a crab claw has set a new records for crustacean size: it is the largest fossilized claw ever found in history. The size indicates that the species may be the ancestor of the current Tasmanian giant crab (Pseudocarcinus gigas), which weighs more than 12 kilos.
The specimen was found on Waitoetoe beach, in New Zealand, on the north island of the archipelago. It was located in the Urenui Formation, which dates back to the Miocene and is part of the Taranaki Basin, which was affected by the Mohakatino eruption. Volcanic ash and mud are sediments capable of optimally preserving fossils, as they cover animals before the ecosystem can start their decomposition.
This type of crab lived in the depths of the sea, and it is the first time one has been found in the New Zealand region. The name given to the new species is Pseudocarcinus karlraubenheimeri, after the amateur paleontologist Karl Raubenheimer, who discovered the specimen when he was just a teenager and made it available to scientists. Its likely descendant, Pseudocarcinus gigas, has claws measuring up to 47 centimeters, the same span as the carapace.
According to scientists, crabs have reached such surprising sizes during their evolution probably due to predators, but also due to competition for prey.
This fossil ancestor is about half the size. As for what drives a crab to become large, the threat of predators plays a role, but it's also about making sure you don't end up with eyes bigger than your shears.
“Pseudocarcinus crabs are characterized by gigantism, which has provided them with significant advantages in competition and defense,”
the authors write.
“Their carnivorous nature is reflected in their exceptionally large greater cheliped [also known as the claw].”
The authors of the discovery suggest that the huge claw size of the Pseudocarcinus karlraubenheimeri may have been driven by an increase in animals such as gastropods and bivalves appearing on the deep-sea menu in the Late Cretaceous, ushering in a new era of LARGE CRABs with LARGE CLAWs.
"This is the largest fossil crab ever discovered, which is fascinating,”
van Bakel added.
“But also, the discovery of its previous habitat: gas seeping from the seabed, bringing CO2 and/or methane to the sediment-water interface, provided a warm, nutrient-rich environment, rich in clams, snails and smaller crabs. This was the food source for these giant crabs! It's great to learn about previous ecosystems.”
The scientific article is available at: https://www.tandfonline.com/doi/full/10.1080/00288306.2024.2314472
