Marrella  splendens

 

The Burgess Shale is the most famous fossil deposit on Earth.  It is located near the town of Field in Yoho National Park, southeastern British Columbia, western Canada.  The deposit is famous for its spectacular soft-bodied preservation - the organisms have had their appendages & internal organs preserved.  Many tens of thousands of fossils have been collected from the Burgess Shale Formation over the last century.  Including known, but unnamed species, and excluding known or demonstrable junior synonyms, the Burgess Shale biota totals at least ~280 species.  (see computer animations of Burgess Shale)

 

Many claim that Charles Walcott discovered the Burgess Shale Lagerstätte (as soft-bodied fossil deposits are called by paleontologists) in 1909.  However, it was actually discovered in 1886 or 1888 by Richard McConnell, based on anomalocarid appendage material from Mt. Stephen, in the Campsite Cliff Member of the Burgess Shale Formation.  The main collecting localities have been two quarries (Walcott Quarry & Raymond Quarry) on the western side of the ridge connecting Mt. Field and Wapta Mountain a little north-northeast of Field.  Numerous other smaller localities have been identified in the same area & for many, many kilometers to the south.  Collecting at the Burgess Shale was most intense in 1910-1917 (Charles Walcott), 1925-1930 (Harvard’s Museum of Comparative Zoology), 1966-1967 (Geological Survey of Canada), and 1975-2000s (Royal Ontario Museum).

 

The most common soft-bodied species in the Walcott Quarry Member  of the Burgess Shale Formation is an odd, small arthropod called Marrella splendens Walcott, 1912.  It cannot be classified with any traditional arthropod group, and several new high-level taxa have been created to accomodate it and other soft-bodied arthropods (e.g., see Hou & Bergström, 1997 - Fossils & Strata 45).

 

Classification: Arthropoda, Lamellipedia, Marrellomorpha, Marrellida, Marrellidae

 

Marrella is quite distinctive - it has two large, curved lateral cephalic spines and a pair of large, posteriorly-directed cephalic spines.  Many Marrella specimens have squeezed-out gut contents (see below).

 

Stratigraphy: Walcott Quarry Member, Burgess Shale Formation, Ptychagnostus praecurrens Interval-zone, lower Marjuman Stage, middle Middle Cambrian.

 

Marrella splendens Walcott, 1912 (~2 cm long, including antennae) from the Burgess Shale (Middle Cambrian) at the Walcott Quarry above Field, British Columbia, Canada.

(YPM 5861, Yale University’s Peabody Museum, New Haven, Connecticut, USA)

 


 

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