| Buenaspis forteyi | |
|---|---|
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Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Order: | †Nektaspida |
| Genus: | †Buenaspis Budd, 1999 |
| Species: | †B. forteyi |
| Binomial name | |
| †Buenaspis forteyi Budd, 1999 | |
| Part of a series on |
| TheCambrian explosion |
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Fossil localities |
Evolutionary concepts |
Buenaspis is agenus of small ( 1 to 3 centimetres (0.39 to 1.18 in) long)nektaspidarthropod, that lived during the earlyCambrian period.[1]Fossil remains ofBuenaspis were collected from theLower CambrianSirius PassetLagerstätte of North Greenland.Buenaspis looks like a soft eyelesstrilobite. It has a headshield (orcephalon) slightly larger than the tailshield (pygidium), and in between them sixthoracic body segments (somites). The genus ismonotypic, its solespecies beingBuenaspis forteyi.
The name of the genus is derived from theBuen Formation, the deposit where the species was collected, and theGreek wordaspis (shield). The species was named in honor ofRichard Fortey, a famed paleontologist.[1]
Buenaspis forteyi is between 1 and 3 cm along the axis, approximately half a wide as long, in general outline shaped as a bar with parallel sides and rounded front and back ends. It is likely the animal was distinctly convex, considering the many concentric crush-marks found in many specimens. Thedorsalexoskeleton consists of a cephalon, a pygidium and six thoracic somites with articulating half-rings, all non-calcified. The cephalon is sub-semicircular, broader than it is long, and with rounded genal angles. Eyes are absent. Antennas are not known. The six thoracic somites are extended into broad posteriorly directed pleural spines, which are free at their tips. The caudal shield is slightly smaller than the cephalic shield, and somewhat more rounded. Some specimens appear to have a lengthwise mid-ridge from the cephalon to the pygidium.[1] Although Budd attributes this feature to deformations, since it does not occur in all specimens known, later authors seem to have accepted it as authentic.[2]
B. forteyi has been collected from the Lower Cambrian (Atdabanian) Buen Formation, Sirius PassetLagerstätte, Peary Land, North Greenland, on the south side of the broad valley known as Sirius Passet at its junction with J.P. Koch Fjord82°47′6″N42°13′7″W / 82.78500°N 42.21861°W /82.78500; -42.21861.[1][4]
Buenaspis forteyi 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.[4]
The author that originally describedBuenaspis and subsequent publications classified the genus as part of the familyLiwiidae. Recently however, Paterson et al. propose to removeBuenaspis from the orderNektaspida entirely, on the argument that it lacks the 'waist' that is a common feature inLiwia,Soomaspis,Tariccoia,Misszhouia,Pseudonaraoia andNaraoia. Also, they regard the ridge on cephalon and pygidium inBuenaspis an artifact, unlike the ridge on the pygidium only inSoomaspis andTariccoia. If Paterson et al. is followed,Buenaspis attains a position somewhere else in theLamellipedia.[5] Other authors have continued to considerBuenaspis a nektaspid, but have placed it outside Liwiidae or any other family.[6]
Data related toBuenaspis at Wikispecies
