Fossil fragments unravel 500-million-year-old predator

March 21st, 2009 - 8:23 pm ICT by IANS  

London, March 21 (IANS) Although described as crustacean-like animal in 1912, Hurdia victoria is just one part of a complex and remarkable new animal that has links with the largest group of living animals, the arthropods.
The fossil fragments have been pieced together from the famous 505 million-year-old Burgess Shale, a Unesco World Heritage Site in British Columbia, Canada. Crustaceans are any aquatic arthropod, such as a lobster or a crab, usually with a segmented body and external skeleton.

This specimen was first classified as an arthropod in the 1970s and 80s, and then as an unusual specimen of the famous monster predator Anomalocaris.

Anomalocaris was a torpedo-shaped, more than a metre long, top-line predator in the Early Cambrian oceans. It had a nasty set of jaws set in a circular mouth.

The new description of Hurdia shows that it is indeed related to Anomalocaris. Like Anomalocaris, Hurdia had a segmented body with a head bearing a pair of spiny claws and a circular jaw structure with many teeth.

But it differs from Anomalocaris by the possession of a huge three-part carapace that projects out from the front of the animal’s head.

Hurdia and Anomalocaris are both early offshoots of the evolutionary lineage that led to the arthropods, the large modern group that contains the insects, crustaceans, spiders, millipedes and centipedes.

Uppsala University researchers Allison Daley and Graham Budd, Department of Earth Sciences, together with colleagues in Canada and Britain, describe the convoluted history and unique body construction of the newly-reconstructed Hurdia victoria, which would have been a formidable predator in its time.

Although the first fragments were described nearly 100 years ago, they were assumed to be part of a crustacean-like animal.

However, collecting expeditions from in the 1990s uncovered more complete specimens and hundreds of isolated pieces that led to the first hints that Hurdia was more than it seemed.

“This structure is unlike anything seen in other fossil or living arthropods,” said doctoral student Allison Daley, who has been studying the fossils for three years as part of her doctoral thesis, according to an Uppsala release.

These findings were published in the Saturday edition of Science.

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