''Aaveqaspis'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of small (about long) marine

arthropod Arthropods ( ) are invertebrates in the phylum Arthropoda. They possess an arthropod exoskeleton, exoskeleton with a cuticle made of chitin, often Mineralization (biology), mineralised with calcium carbonate, a body with differentiated (Metam ...

s of unclear affiliation, that lived during the early

Cambrian The Cambrian ( ) is the first geological period of the Paleozoic Era, and the Phanerozoic Eon. The Cambrian lasted 51.95 million years from the end of the preceding Ediacaran period 538.8 Ma (million years ago) to the beginning of the Ordov ...

period.

Fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

remains of ''Aaveqaspis'' were collected from the Lower

Sirius Passet Sirius Passet is a Cambrian Lagerstätte in Peary Land, Greenland. The Sirius Passet Lagerstätte was named after the Slædepatruljen Sirius, Sirius sledge patrol that operates in North Greenland. It comprises six places in Nansen Land, on the eas ...

fossil-Lagerstätte of North Greenland. ''Aaveqaspis'' looks like a soft eyeless

trilobite Trilobites (; meaning "three-lobed entities") are extinction, extinct marine arthropods that form the class (biology), class Trilobita. One of the earliest groups of arthropods to appear in the fossil record, trilobites were among the most succ ...

with a weakly defined axis, a headshield (or

cephalon Cephalon, Inc. was an American biopharmaceutical company co-founded in 1987 by pharmacologist Frank Baldino Jr., Frank Baldino, Jr., neuroscientist Michael Lewis, and organic chemist James C. Kauer—all three former scientists with the DuPont ...

) with stubby genal spines, 5 thorax segments also ending in stubby genal spines, and a tailshield (

pygidium The pygidium (: pygidia) is the posterior body part or shield of crustaceans and some other arthropods, such as insects and the extinct trilobites. In groups other than insects, it contains the anus and, in females, the ovipositor. It is compos ...

) with a pair of massive tusk-like spines, and two smaller spines near the end of the axis. The only species presently known is ''A. inesoni'' (i.e. the genus is

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...

Etymology

The name of the genus is a compound of the Greenlandic word (), reflecting the likeness of the tail spines to the tusks of a walrus, and the

Ancient Greek Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek ...

word (; ). The species was named after Jon R. Ineson to honour him for his studies of the Cambrian of North Greenland.

Description

''Aaveqaspis inesoni'' is almost flat (dorso-ventrally). Its body is narrowly oval in general outline, disregarding the two large spines. The upper non-calcified (or dorsal) side of the body consists of a cephalon, 5 thorax segments, and a pygidium. The axis is slightly raised, but without a discernible furrow defining its outline. The axis is about 20% of the width of the cephalon. The cephalon is half-round, and almost twice as wide as long (along the axis). The (posterolateral) corners of the cephalon are acute, ending in short stout spines. The back margin of the cephalon from the spine to the midline has in the pleural region a forward angle and is first concave, then convex, then concave again, attaining a backward angle when reaching the axis, and finally convex, with a small node or median spine reaching the back margin. This pattern is repeated with all thorax segments. Antennae are not known. Dorsal eyes are absent. The thorax segments are each about along the axis. The tail shield is dominated by a pair of large segmental marginal spines, reminiscent of large (or macropleural) spines in the thorax and of pygidial spines of certain trilobites. The one node it carries is larger and more sharply defined than the nodes on the segments. The frontal border of the tail shield is convex and curves laterally into the large spines which extend postero-laterally, constituting half the total body length. The back margin of the spines is concave and merges into the second pair of short, broad, triangular spines. Body parts on the belly (or ventral) side are not known, including any appendages.

Distribution

''A. inesoni'' has been collected from the Lower Cambrian (Atdabanian)

Buen Formation The Buen Formation is a Formation (geology), geologic formation and Lagerstätte in Peary Land, North Greenland. The shale preserves fossils dating back to the Early Cambrian Period (geology), period (Atdabanian in the local timescale, about 520 ...

, Sirius Passet Fossil-Lagerstätte, Peary Land, North Greenland, , on the south side of the broad valley known as Sirius Passet at its junction with J. P. Koch Fjord.

Habitat

''Aaveqaspis inesoni'' was probably a marine bottom dweller, that lived in deeper water. This may be deduced from the dominance of eyeless forms and the absence of seaweeds at the collection site.

Taxonomic position

The taxonomic position of ''A. inesoni'' is unclear.

References

External links

* {{Taxonbar, from=Q18707590 Prehistoric arthropod genera Cambrian arthropods Cambrian Greenland Fossils of Greenland Sirius Passet fossils Buen Formation Fossil taxa described in 2009 Cambrian genus extinctions