NMMNH 3642, Anton Chico: Aegean - Bithynian, New Mexico
collected by Alex Velasquez, NMMNH field crew 1997-1998
List of taxa
Where & when
Geology
Taphonomy & methods
Metadata & references
Taxonomic list
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unclassified
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Plantae indet.
Haeckel 1866
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Branchiopoda
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Conchostraca indet.
Sars 1867
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Ostracoda
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Ostracoda indet.
Latreille 1802
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Anomodontia
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? Dicynodontia indet.
(Owen 1859)
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2 specimens | |||||||||
| Cross section of limb bone and paired ?girdle fragments; may represent a single individual | ||||||||||
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Reptilia
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Archosauriformes informal new species
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2 individuals | |||||||||
| NMMNH P-27269, P-43257, partial postcrania. May be an erythrosuchid or a basal crocodile-line archosaur | ||||||||||
| see common names | ||||||||||
Geography
| Country: | United States | State/province: | New Mexico | County: | Guadalupe |
| Coordinates: | 35.2° North, 105.1° West (view map) | ||||
| Paleocoordinates: | 1.8° North, 34.9° West | ||||
| Basis of coordinate: | based on nearby landmark | ||||
| Geographic resolution: | small collection |
Stratigraphy
| Formation: | Moenkopi | Member: | Anton Chico | ||
| Stratigraphic resolution: | bed | ||||
| Stratigraphy comments: 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 | |||||
Lithology and environment
| Primary lithology: | planar lamination,gray lithified mudstone |
| Secondary lithology: | burrows,gray lithified sandstone |
| Includes fossils? | Y |
| Lithology description: "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" | |
| Environment: | lacustrine - small |
| Geology comments: "We interpret NMMNH locality 3642 to be part of a locally restricted lacustrine deposit that preserves a succession of biotic conditions" | |
Taphonomy
| Modes of preservation: | body |
| Size of fossils: | macrofossils,mesofossils |
| Preservation of anatomical detail: | poor |
| Disassociated major elements: | some |
| Disassociated minor elements: | some |
| Spatial resolution: | parautochthonous |
Collection methods and comments
| Collection methods: | bulk,selective quarrying,field collection | ||
| Reason for describing collection: | taxonomic analysis | ||
| Museum repositories: | NMMNH | ||
| Collectors: | Alex Velasquez, NMMNH field crew | Collection dates: | 1997-1998 |
| Collection method comments: Vertebrae, ribs, pelvic and limb bones collected as float; gastralia, osteoderms and invertebrates collected in situ. | |||
Metadata
| Database number: | 88068 | ||
| Authorizer: | R. Butler | Enterer: | R. Butler |
| Modifier: | R. Butler | Research group: | vertebrate |
| Created: | 2009-03-31 08:51:51 | Last modified: | 2012-10-25 03:31:49 |
| Access level: | the public | Released: | 2009-03-31 08:51:51 |
| Creative Commons license: | CC BY |
Reference information
Primary reference:
| 29585. | 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] |