A PROBABLE ANNELID FROM THE UPPER PENNSYLVANIAN (VIRGILIAN) ATRASADO FORMATION (MADERA GROUP) OF CENTRAL NEW MEXICO

The Upper Pennsylvanian (Virgilian) Kinney Quarry Lagerstätte in the Manzanita Mountains of central New Mexico contains a diverse floral and faunal fossil assemblage that has been documented in an extensive literature. Here, we add a new record to the Kinney assemblage—a probable annelid body fossil. The specimen (NMMNH P-40215) is preserved, without a counterpart, on a small piece of laminated calcareous shale from Kinney unit 3, which also produces insects and myriapods. The paleoenvironment has been interpreted as lagoonal.

The specimen appears as a laterally compressed body impression coiled into a C-shape. There are two separate portions due to a section missing from the mid-length. The body width varies, with the ?posterior end being three times the width of the ?anterior end. The ?posterior measures 3 mm at its greatest width and the ?anterior portion measures 1 mm in width. The length along the central axis is 14 mm, and the annuli are narrow and closely spaced. There is a differentially preserved carbonized area at the ?posterior end.

The presence of annuli is indicative of Annelida. Some annuli appear to diverge, as do the veins in certain contemporaneous plants or as in insect wings, but in this specimen such divergence probably reflects taphonomic processes. The lack of parapodia or conspicuous chaetae is characteristic of some annelid groups, including leeches. It is possible that the ?terminal carbonized area is a posterior sucker. The morphology of this fossil, consisting of proportionally different anterior and posterior body widths with closely spaced narrow annuli, and the possible presence of a sucker, is indicative of leeches, which have a very sparse fossil record possibly extending to the Silurian. The Kinney specimen, if it is a leech, appears to differ from the more elongate forms described as certain leeches from the Jurassic of Germany and those described as possible leeches from the Silurian of Wisconsin.

Polychaete (Spirorbis) tube casts and two unassigned wormlike specimens lacking the annulations found on P-40215 have been the only previous records of annelids from the Kinney Quarry locality.