Aciculopoda is an extinct Dendrobranchiata which existed in what is now Oklahoma approximately . It was described in 2010 on the basis of a single fossil from Oklahoma. The single species, Aciculopoda mapesi, was named by Rodney Feldmann and Carrie Schweitzer in honour of Royal Mapes, a paleontologist who discovered the type specimen.
Discovery
The fossil was discovered in the
Woodford Shale, exposed at the Ryan Quarry, in Pontotoc County,
Oklahoma. The Woodford Shale is a dark-colored
Silicon dioxide shale which
to the north-east and the south-west of the Arbuckle Mountains in Oklahoma. It contains "
,
,
,
Ammonite and
nautiloid , inarticulate
... and small
Phyllocarida ",
and spans the
Devonian–
Carboniferous boundary. The
stratum which produced
Aciculopoda are thought on the basis of conodont
biostratigraphy to be from the
Famennian.
Description
The
holotype of
Aciculopoda mapesi is housed at the United States National Museum as lot USNM 540766.
The animal is long, of which the
anterior is the
cephalothorax. The pleon (abdomen) is around long, along its curved dorsal margin, and about deep at its base. The cuticle is missing from the pleon, exposing the well-preserved
beneath.
Etymology
The genus name
Aciculopoda is said to be derived from the
Latin acicula]] ("needle") and "
poda" ("foot"), referring to the sharp spines on the
.
is however used for "foot" in classical Latin,.
[Lewis, C.T. & Short, C. (1879). A Latin dictionary founded on Andrews' edition of Freund's Latin dictionary. Oxford: Clarendon Press.] while in ancient Greek,
pous (πούς) is used.
[Liddell, H.G. & Scott, R. (1940). A Greek-English Lexicon. Revised and augmented throughout by Sir Henry Stuart Jones with the assistance of Roderick McKenzie.Oxford: Clarendon Press.] The specific epithet commemorates Royal Mapes, who discovered the specimen and has published widely on fossil crustaceans.
Interpretation
The only unambiguous
Decapoda fossil older than
Aciculopoda is
Palaeopalaemon, found in Devonian sediments in
Ohio. (The assignment of
Imocaris to the Decapoda is the subject of some debate.) The fact that both
Aciculopoda and
Palaeopalaemon were discovered in the
United States led Feldmann & Schweitzer to suggest that their common ancestor, the most recent common ancestor of the
Decapoda may also have originated in the ancient continent
Laurentia.
