NMMNH 3642, Anton Chico (Triassic to of the United States)

Where: Guadalupe County, New Mexico (35.2° N, 105.1° W: paleocoordinates 1.8° N, 34.9° W)

• coordinate based on nearby landmark

• small collection-level geographic resolution

When: Anton Chico Member (Moenkopi Formation), Aegean to Aegean (247.2 - 242.0 Ma)

• Upper part of the Anton Chico member; equivalent to the Holbrook Member of the Moenkopi formation in Arizona

•

•Lucas & Schoch (2002: Lethaia 35: 97-106) inferred the Holbrook member to be earliest Anisian (Aegean–Bithynian) in age based upon tetrapod biostratigraphy (Eocyclotosaurus used to correlate Holbrook Member to German Upper Bundsandstein) and magnetostratigraphy

• bed-level stratigraphic resolution

Environment/lithology: lacustrine - small; lithified, gray mudstone and lithified, burrowed, gray sandstone

• "We interpret NMMNH locality 3642 to be part of a locally restricted lacustrine deposit that preserves a succession of biotic conditions"
• "The fossiliferous internal at NMNH locality 3642 starts with a 20-30 cm thick olive gray sandstone, overlain by a light gray sandstone that grades upward into finely laminated gray mudstone...the basal sandstone has an erosional base and locally contains invertebrate trace fossils (burrows). It is topped by a coarse siltstone that grades into a conglomerate laterally, which is rich in 10-20 cm long plant remains, mostly small tree trunks. Starting with this siltstone, the abundance and diversity of conchostrachans (estherians) increases markedly, while the frequency and size of plant material descreases towards the top of the succession. The gray mudstone has the highest abundance of conchostracans and may contain bivalves, although confined to a few horizons. The reptile bones (mainly scutes and gastralia) were found in the topmost horizon of the exposed section, which is particularly rich in vertebrate coprolites with lengths of 1 to 3 cm"

Size classes: macrofossils, mesofossils

Collected by Alex Velasquez, NMMNH field crew in 1997-1998; reposited in the NMMNH

Collection methods: bulk, quarrying,

• Vertebrae, ribs, pelvic and limb bones collected as float; gastralia, osteoderms and invertebrates collected in situ.

Primary reference: S. J. Nesbitt, S. G. Lucas, and R. R. Schoch. 2006. A new, large archosauriform from the Anton Chico Member of the upper Moenkopi Formation (Middle Triassic), east-central New Mexico, USA. Neues Jahrbuch für Geologie und Paläontologie Abhandlungen 239(2):289-311 [R. Butler/R. Butler]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 88068: authorized by Richard Butler, entered by Richard Butler on 31.03.2009

Creative Commons license: CC BY (attribution)

Taxonomic list

Show authors, comments, and common names
Reptilia
 Diapsida -
Archosauriformes "new species"
Archosauriformes "new species" Gauthier 1986 archosauromorph
NMMNH P-27269, P-43257, partial postcrania. May be an erythrosuchid or a basal crocodile-line archosaur
Osteichthyes
 Dicynodontia -
? Dicynodontia indet.
? Dicynodontia indet. Owen 1859 dicynodont
Cross section of limb bone and paired ?girdle fragments; may represent a single individual
Branchiopoda
 Diplostraca -
Conchostraca indet.
Conchostraca indet. Sars 1867 clam shrimp
Deuteropoda
  -
Ostracoda indet.
Ostracoda indet. Latreille 1802 ostracod
unclassified
  -
Plantae indet.
Plantae indet. Haeckel 1866