PTEROCEPHALIA FROM THE MCKAY GROUP

A lovely Pterocephalia trilobite from Upper Cambrian, Furongian strata of the McKay Group, Kootenay Rockies. 

The McKay Group has been explored extensively these past few years by Chris New and Chris Jenkins of Cranbrook, British Columbia. 

Together, these two avid trilobite enthusiasts have opened up considerable knowledge on the exposures, collaborating with researchers such as Brian Chatterton and Rudy Lerosey-Aubril. They have unearthed many new specimens and several new species. 

Pterocephalia from this region are relatively common. It was the keen eyes of Chris Jenkins that spotted the unusual preservation of the gut tract that led to the publication by Chatterton et al. in 1994. 

Rudy Lerosey-Aubril published a paper in 2017 on phosphatized gut remains — relatively common in this taxon at this site. Lerosey-Aubril’s paper was on an aglaspidid, a combjelly, and the gut of another trilobite. 

Skeletal remains of trilobites are abundant in Palaeozoic rock but soft parts are rarely preserved. There have been a few papers on trilobite gut remains from Canada and on abundant trilobite faunas of the Kaili Formation of Guizhou, China. The Kaili contains one of the earliest middle Cambrian Burgess Shale-type deposits, sharing many faunal elements (see http://hdl.handle.net/1811/24227) with the older Chengjiang Biota (Chen 2004; Hou et al. 2004) and the younger Burgess Shale Biota (Briggs et al. 1994). 

The biota, facies description, and regional stratigraphy of the Kaili Biota were discussed and reviewed in Zhao et al. (2002, 2005) and Lin et al. (2005). Chinese colleagues (Zhao et al. 1994b, 1996, 1999, 2001, 2002) have illustrated many Kaili arthropods with soft-part preservation, but most of their systematic descriptions are yet to be completed.

References: Chatterton BD, Johanson Z, Sutherland G. 1994. Journal of Paleontology 68:294-305. 

Lin, Jih-Pai. (2007). Preservation of the gastrointestinal system in Olenoides (Trilobita) from the Kaili Biota (Cambrian) of Guizhou, China. Memoirs of the Association of Australasian Palaeontologists. 33. 179-189. 

Photo: This specimen was collected by Dan Bowden and photographed by the Huntress. It has been checked for the dark telltale signs of phosphatized gut remains, but sadly no luck!

THE DUDLEY BUG

Calymene blumenbachii, Theresa Paul Spink Dunn

A lovely example of the trilobite Calymene blumenbachii from outcrops in the UK. This wee rolled beauty is in the collections of Theresa Paul Spink Dunn. This Silurian trilobite is from the Homerian, Wenlock Series, Wrens Nest, Dudley, UK.

Calymene blumenbachii, sometimes erroneously spelled blumenbachi, are found in the limestone quarries of the Wren's Nest in Dudley, England. This locality name was charmingly highjacked by an 18th-century quarryman birth the nickname the Dudley Bug — both a symbol of the town and a key feature on the Dudley County Borough Council Coat-of-Arms. Calymene blumenbachii is commonly found in Silurian rocks — 422.5-427.5 million years ago — that formed near shallow water, low energy reefs.

This particular species of Calymene — a fairly common genus in the Ordovician-Silurian — is unique to the Wenlock series in England and comes from the Wenlock Limestone Formation in Much Wenlock and the Wren's Nest in Dudley. These sites seem to yield trilobites more readily than any other areas on the Wenlock Edge. The rock here is dark grey and quite fossiliferous. Just a few miles away in Church Stretton and along other parts of the Edge, it is yellowish or whitish — an indication that there were local changes in the environment in which the rock was deposited. The Wenlock Edge quarry is closed to further collecting but may reopen for future research projects.

HYPODICRANOTUS STRIATULUS OF ONTARIO

Hypodicranotus striatulus

Take a gander at this unusual trilobite, Hypodicranotus striatulus (Walcott, 1875), with his gloriously bulbous head shield. Missing from this specimen is the wonderful forked hypostome from the dorsal exoskeleton that marks him as H. striatulus.

He’s from outcrops in the Verulam Formation, Bowmanville, Ontario, Canada. He lived in a deep subtidal environment as a nektobenthic deposit feeder some 460.9 to 449.5 million years ago.

These extinct pelagic trilobites are in the order Asaphida in the family Remopleuridae. Specimens have been found in Middle Ordovician marine outcrops from Ontario, Canada (this fellow is from here), the Northwest Territories, Quebec and in New York State, United States. Some of his sister taxa also in Remopleurididae (Hawle and Corda, 1847)  have been found in the Northwest Territories, Quebec, the UK and in Iowa, Wisconsin and Nevada. Collection of the awesome Marc R. Hänsel

FRENCHMAN MOUNTAIN TRILOBITE: BRISTOLIA INSOLENS

Bristolia insolens

A stunning Cambrian trilobite, Bristolia insolens, from Frenchman Mountain near Las Vegas, Nevada.

The mountain provides an example of the Great unconformity with the tilted Paleozoic Tapeats Sandstone underlain by Paleoproterozoic Vishnu Schist. An unconformity is a buried erosional or non-depositional surface separating two strata of different ages. We know when we find these that the sediment was not laid down in a continuous deposition. The range also boasts some of the oldest rock on the North American continent, at about two billion years old.

This spectacular specimen is in the collection of York Yuxi Wang. It is about 4-5cm long; 3-4cm wide.

WANNERIA DUNNAE

Wanneria dunnaeis an impressive trilobite from British Columbia's Eager Formation, and one of the more striking specimens found at the original research site of the lovely Lisa Bohach, a paleontologist now working out of Alberta.

The site has changed over the years, both physically and politically, but the one constant is the exquisite detail of the specimens. Both Wanneria dunnae and Ollenelus ricei are commonly found here. I had a eureka moment there a few years ago when ambling up the path to the main pit. The sun hit a wily would-be hiking track on a bit of shale at just the right angle. Closer inspection showed it to be a Tuzoia, one of the rare arthropods to come from the area.

THE CAMBRIAN: 570 MILLION YEARS AGO

The Cambrian was a time of expansion for the Earths more complex animal forms. Molluscs and arthropods or their friends with hard shells and exoskeletons dominated the seas. The photo is of a Wanneria dunnae from the Eager Formation, Rifle Range site near Cranbrook from a trip in 1990.

Cambrian Fossil Sites in Western Canada:

Tanglefoot and Eager Formation Trilobites, Mount Field Burgess Shale Soft-bodied marine critters and the fossils from the Mount Stephen Trilobite beds.