Sirius Passet
Encyclopedia
Sirius Passet is a Cambrian
Cambrian
The Cambrian is the first geological period of the Paleozoic Era, lasting from Mya ; it is succeeded by the Ordovician. Its subdivisions, and indeed its base, are somewhat in flux. The period was established by Adam Sedgwick, who named it after Cambria, the Latin name for Wales, where Britain's...

 Lagerstätte
Lagerstätte
A Lagerstätte is a sedimentary deposit that exhibits extraordinary fossil richness or completeness.Palaeontologists distinguish two kinds....

 in Greenland
Greenland
Greenland is an autonomous country within the Kingdom of Denmark, located between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago. Though physiographically a part of the continent of North America, Greenland has been politically and culturally associated with Europe for...

. The Sirius Passet Lagerstätte was named after the Sirius sledge patrol that operates in North Greenland. It comprises six localities located on the eastern shore of J.P. Koch Fjord in the far north of Greenland. It was discovered in 1984 by A. Higgins of the Geological Survey of Greenland. A preliminary account was published by Simon Conway Morris
Simon Conway Morris
Simon Conway Morris FRS is an English paleontologist made known by his detailed and careful study of the Burgess Shale fossils, an exploit celebrated in Wonderful Life by Stephen Jay Gould...

 and others in 1987, but since then, expeditions led by J. S. Peel and Simon Conway Morris
Simon Conway Morris
Simon Conway Morris FRS is an English paleontologist made known by his detailed and careful study of the Burgess Shale fossils, an exploit celebrated in Wonderful Life by Stephen Jay Gould...

 have returned to the site several times between 1989 and the present. A field collection of perhaps 10,000 fossil specimens has been amassed.

The fauna is inevitably compared to that of the Burgess Shale
Burgess Shale
The Burgess Shale Formation, located in the Canadian Rockies of British Columbia, is one of the world's most celebrated fossil fields, and the best of its kind. It is famous for the exceptional preservation of the soft parts of its fossils...

, although it is probably ten to fifteen million years older – 518 vs. 505 Ma (Martin et al. 2000; Nevadella zone, stage 3 of Cambrian Series 2) – and more closely contemporaneous with that from Chengjiang
Maotianshan shales
The Maotianshan Shales are a series of lower Cambrian deposits in the Chiungchussu formation, famous for their Konservat Lagerstätten, or high number of fossils preserved in place...

.

Although the fauna has not yet been fully described, it is known to consist of a moderate number of arthropods and sponges, together with rare representatives of other groups. It has yielded three highly problematic taxa, Halkieria
Halkieria
Halkieria is a genus of fossil organisms from the Lower to Middle Cambrian. It has been found on almost every continent in Lower to Mid Cambrian deposits, forming a large component of the small shelly fossil assemblages...

, Kerygmachela and Pambdelurion, all of which have played prominent roles in discussions about the origins of the modern animal phyla.

In early 2008, Simon Conway Morris
Simon Conway Morris
Simon Conway Morris FRS is an English paleontologist made known by his detailed and careful study of the Burgess Shale fossils, an exploit celebrated in Wonderful Life by Stephen Jay Gould...

 published another paper describing a polychaete
Polychaete
The Polychaeta or polychaetes are a class of annelid worms, generally marine. Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are made of chitin. Indeed, polychaetes are sometimes referred to as bristle worms. More than 10,000...

 annelid
Annelid
The annelids , formally called Annelida , are a large phylum of segmented worms, with over 17,000 modern species including ragworms, earthworms and leeches...

 from the Sirius Passet. As SCM et al. note in their discussion, "the phyletic position of Phragmochaeta is very poorly constrained, but it may be fairly basal", which is what makes these early Cambrian
Cambrian
The Cambrian is the first geological period of the Paleozoic Era, lasting from Mya ; it is succeeded by the Ordovician. Its subdivisions, and indeed its base, are somewhat in flux. The period was established by Adam Sedgwick, who named it after Cambria, the Latin name for Wales, where Britain's...

 Lagerstätte
Lagerstätte
A Lagerstätte is a sedimentary deposit that exhibits extraordinary fossil richness or completeness.Palaeontologists distinguish two kinds....

 so fascinating. Polychaete annelids are a significant component of the Burgess Shale
Burgess Shale
The Burgess Shale Formation, located in the Canadian Rockies of British Columbia, is one of the world's most celebrated fossil fields, and the best of its kind. It is famous for the exceptional preservation of the soft parts of its fossils...

 fauna, but are otherwise unknown from the other early Cambrian
Cambrian
The Cambrian is the first geological period of the Paleozoic Era, lasting from Mya ; it is succeeded by the Ordovician. Its subdivisions, and indeed its base, are somewhat in flux. The period was established by Adam Sedgwick, who named it after Cambria, the Latin name for Wales, where Britain's...

 Lagerstätte
Lagerstätte
A Lagerstätte is a sedimentary deposit that exhibits extraordinary fossil richness or completeness.Palaeontologists distinguish two kinds....

, so this single species from a single locality appreciably extends the depth of understanding of this group. Unfortunately, the material so far described from Sirius Passet is sparse in morphological characters.

Simon Conway Morris
Simon Conway Morris
Simon Conway Morris FRS is an English paleontologist made known by his detailed and careful study of the Burgess Shale fossils, an exploit celebrated in Wonderful Life by Stephen Jay Gould...

 notes in this most-recent paper that the study is being done on "almost 6000 fossiliferous slabs ... selected during visits between 1985 and 2006 from extensive talus slopes derived from the lower part of the Buen Formation", with indications that other outcrops of potentially fossiliferous material are known, but are under-explored.

Taxa from the Sirius Passet fauna

Halkieria evangelista
Halkieria
Halkieria is a genus of fossil organisms from the Lower to Middle Cambrian. It has been found on almost every continent in Lower to Mid Cambrian deposits, forming a large component of the small shelly fossil assemblages...



Buenaspis forteyi

Kerygmachela kierkegaardi
Kerygmachela kierkegaardi
Kerygmachela kierkegaardi was a blind nektonic organism from the Sirius Passet Lagerstätte, from Cambrian Greenland. Its anatomy strongly suggests that it, along with its relative Pambdelurion whittingtoni, was either an anomalocarid or a close relative thereof...



Pambdelurion whittingtoni
Pambdelurion whittingtoni
Pambdelurion whittingtoni was a blind nektonic organism from the Sirius Passet Lagerstätte, from Cambrian Greenland. Its anatomy strongly suggests that it, along with its relative Kerygmachela kierkegaardi, was either an anomalocarid or a close relative thereof.P...



Hadranax augustus
Hadranax
Hadranax augustus is a xenusiid lobopod known from the lower Cambrian Sirius Passet lagerstatte....



Buenellus higginsi

Kleptothule rasmusseni
Kleptothule rasmusseni
Kleptothule rasmusseni was a small, elongated trilobite, about 3 cm in length, and about 5 to 6 mm in width, from the Sirius Passet Lagerstätte. It is currently placed in the family Nevadiidae, though this may change with further study....



Pauloterminus spinodorsalis

Phragmochaeta canicularis

Kiisortoqia soperi
Kiisortoqia
Kiisortoqia soperi is a species of arthropod from the Early Cambrian Sirius Passet in Greenland. Its antennulae resemble anomalocaridid great appendages.- Morphology :...

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