Fossil Fragments Reveal 500-million-year-old Monster Predato

[drwayne]

ScienceDaily (Mar. 21, 2009) — Hurdia victoria was originally described in 1912 as a crustacean-like animal. Now, researchers from Uppsala University and colleagues reveal it to be just one part of a complex and remarkable new animal that has an important story to tell about the origin of the largest group of living animals, the arthropods.

The fossil fragments puzzled together come from the famous 505 million year old Burgess Shale, a UNESCO World Heritage Site in British Columbia, Canada. Uppsala researchers Allison Daley and Graham Budd at the 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 one hundred years ago, they were assumed to be part of a crustacean-like animal. It was not then realised that other parts of the animal were also in collections, but had been described independently as jellyfish, sea cucumbers and other arthropods. 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. The last piece of the puzzle was found when the best-preserved specimen turned up in the old collections at the Smithsonian National Museum of Natural History, Washington DC. 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.

Rest of the story:

http://www.sciencedaily.com/releases/20 ... 142403.htm

[starsinmyeyes44]

That is one cool-looking creature!
One of my favorite classes in undergraduate college was Invertebrate Zoology...this would have been one heck of a specimen to study.

[ed_pardo]

Take a look at this paper:

The stem crustacean Oelandocaris oelandica revisited
Martin Stein, Dieter Waloszek, Andreas Maas, Joachim T. Haug, and Klaus J. Müller
Acta Palaeontologica Polonica 53 (3), 2008: 461-484
The arthropod Oelandocaris oelandica from the upper Middle Cambrian “Orsten” of Sweden was recently recognized as a member of the early phase of crustacean evolution based on additional morphological detail from new specimens. Here we present a detailed investigation of all available material. It includes the description of a 400 ?m long specimen probably representing an early developmental stage. Variation in size correlated with variation of trunk?segment numbers allowed recognition of different instars. The largest specimens do not exceed an estimated length of about 1 mm, indicating that our material may consist only of immature specimens. The characteristic, extremely long antennula of O. oelandica branches into three long rods. It may have served as the major structure to sweep in food, aided by the two subsequent appendages. These and the more posterior limbs were also responsible for locomotion. Minute pores on the outer edges of the posterior limbs and on the trunk tergites possibly contained sensilla originally, which may have served as water?current detectors. The presence of a minute proximal endite only on the third head appendage suggests a rather basal position of this species within Crustacea, because comparable developmental stages of other known stem crustaceans have such an endite on more of their appendages. Reconstruction of O. oelandica and its life attitudes (referred to the largest instar known) benefited from the application of 3D modelling. These helped, e.g., in identifying the combination of the plesiomorphic feeding function of the antennulae and the specialisation of the exopods of the next two appendages as a step toward the development of a sweep?net mode of feeding, one of the key novelties in the evolution of Crustacea. Such a mode of feeding coupled with locomotion of the three anterior appendages is still practiced in the naupliar and metanaupliar phases of many extant eucrustaceans, and even some adults.

http://www.app.pan.pl/archive/published ... 53-461.pdf

Other than the (missing) mouth parts it is very similar, IMO closer than Anomalocaris.

[DinoDan]

This is sure a king of the arthropods and the biggest crab ever. There are alot of things that are needed to answer. Do you have any questions about this animal?

[secularhumanizinevoluter]

Haven't they found Trilobite fossils with chunks bitten out that match the mouth parts of this critter? And as far as "biggest crab ever" just how big is the latgest one they've found?

[ed_pardo]

Haven't they found Trilobite fossils with chunks bitten out that match the mouth parts of this critter? And as far as "biggest crab ever" just how big is the largest one they've found?

Yes, I had read about that a while ago. The grand pappy of the one in question had been searched for it for a long time because of the bites taken out of Trilobites. When I was a kid the mouth parts had thought that they were different small animals but finally figured out that they were all parts of a bigger animal. Now they figured out that they did not go extinct as far back as they had originally thought. It's family turns out was around for a very long time. The design was apparently an efficient predator.