November 9th, 2015
High up in the Rocky Mountains of Alberta and British Columbia, Canada, there is an extensive outcrop of sedimentary rock, a piece of which is the infamous Burgess Shale formation. A healthy majority of all that we know about the Cambrian Explosion comes from fossil finds made here during the past 100 years or so, due to the unique circumstances in which the formation came to be – the seabed of a continental shelf, that got struck by an earthquake causing the critters to be buried in the extremely fine sediment. The fine sediment enabled the entirety of an animal’s anatomy to be preserved, which is extremely rare in the fossil world.
The latest news to feature the Burgess Shale fauna has been in relation to a rather prickly worm-like creature that has recently been shown to have prickly relatives worldwide.
The prickly worm is called Hallucigenia. The scientists that unearthed the first fossils of this pint-sized anomaly felt that they surely must’ve been hallucinating.
Those first fossils were found in the Burgess Shale formation.
There have recently been so many finds relating to the Hallucigenia neck of the woods that scientists can now tentatively link Hallucigenia and its kin to the branch that includes water bears (tardigrades), and ultimately relate them back to the first worm-shaped, arthropod ancestors:
Another Cambrian era freak that’s been packing on the phylogenetic relatives at the Burgess shale recently has been Anomalocaris. As with Hallucigenia, relatives of Anomalocaris are also being found elsewhere on Earth.
Here’s the lot of them:
These were the very first ever predators on planet Earth. They would ‘grab’ their prey with the claws at the front of their head, and use those claws to shove the prey into their ring-shaped mouth. They’re an evolutionary dead-end, however.
Yet another recent find at the Burgess formation has been the discovery of a free-swimming mollusc dating back to the Cambrian.
The specimen, Nectocaris, once thought to be a shrimp relative, is now confirmed to be an early squid and octopus relative, in reality.
More on our side of the evolutionary tree, one of the earliest specimens, possibly belonging to a modern, rather weird-looking group of animals called Echinoderms, was also dug up from the shale.
The creature is named Herpetogaster.
The most recognizable echinoderms are the starfish, sand-dollars, and sea urchins. Other members of the family include sea cucumbers and crinoids.
For more weird animals that have been found at the Burgess Shale formation, here’s Wikipedia on the matter: http://en.wikipedia.org/wiki/Burgess_shale_fauna#Burgess_Shale
burgess shales fossils, cambrian fossils