Burgess Shale Leanchoilia superlata

Great Appendage Arthropoda

Leanchoilia superlata

Phylum Arthropoda

Geological Time: Early Cambrian, (~520 million years ago)

Size: Fossil is 73 mm overall, plus 25 mm appendage

Fossil Site: Burgess Shale, Stephen Formation, Burgess Pass, British Columbia, Canada

Leanchoilia superlata from Burgess ShaleDescription: Leanchoilia superlata is an unusual arthropod found in the Burgess Shale Fauna of British Columbia. It is a member of a group of “great appendage arthropods” known as opabinids after the bizarre Opabinia from the Burgess Shale. It is possibly also known from Utah and Greenland, and has an older relative Leanchoilia illecebrosa found in the Chengjiang Biota of China.

The contrast between the specimen and the matrix has been enhanced by a chemical process that removed some of the Leanchoiliamatrix overburden. Before photos below show the difference such treatment makes. Since the specimen is typically covered with resistant mica and is composed of the carbonized remains of the animal, it is inert to the treatment. The result you see here is all natural. There has been no paint added to bring out detail. This wonderful example shows incredible detail for a specimen more than a half billion years of age as the Cambrian Explosion was in full bloom. Notice the upturned “snout,” the sweeping appendages, body segments, and gut trace as well as the gill filaments of the biramous swimming appendages. The speciomen displays the characteristic sheen for which Burgess specimens are famous. Additionally, there is a partial second example to be seen at the lower right. It occurs at a slightly lower horizon than the main specimen, and shows only a small portion of the anteriormost part of the specimen, including a partial appendage. Leanchoilia superlata is also quite rare in the Burgess Shale: for each 1000 Burgess specimens only 2 are Leanchoilia; even fewer are as complete in this excellent fossil.

click to enlarge

Unprepped fossil below

Fossil Museum Navigation:
Fossils Home
Geological Time Paleobiology Geological History Tree of Life
Fossil Sites Fossils Evolution Fossil Record Museum Fossils