Barrel Springs arroyo (UNM V-143) (Cretaceous of the United States)

Also known as Alamosaurus type site, Bauer 67, NMMNH Loc. L-4225

Where: San Juan County, New Mexico (36.3° N, 108.0° W: paleocoordinates 43.6° N, 85.7° W)

• coordinate stated in text

• outcrop-level geographic resolution

When: Naashoibito Member (Ojo Alamo Formation), Late/Upper Maastrichtian (70.6 - 66.0 Ma)

• from lower part of layer at this site

•Flynn et al. 2020: The mammalian faunas of the Naashoibito Member correlates to the Lancian Land Mammal Age, which suggests a late Maastrichtian age (Williamson and Weil, 2008a). Paleobotanical analyses on the megaflora and pollen indicates that the Ojo Alamo Sandstone is earliest Paleocene in age and is correlated with palynostratigraphic zones P1 or P2 ( Anderson, 1959; Nichols, 2003; Williamson et al., 2008; Flynn and Peppe, in press). Recent detrital sanidine and paleomagnetic work has constrained the Naashoibito Member to the latest Maastrichtian indicating the K/Pg boundary is represented by the unconformity between the Naashoibito Member and the Ojo Alamo Sandstone (Peppe et al., 2013; Flynn et al., 2019). These data, coupled with previous sedimentological analyses, demonstrate that the Naashoibito Member is late Maastrichtian in age and the Ojo Alamo Sandstone is early Paleocene in age with an erosive unconformity, that cuts out the Cretaceous-Paleogene boundary, separating the two units

• bed-level stratigraphic resolution

Environment/lithology: "channel"; concretionary, brown, white, conglomeratic sandstone

• "Sandstone, soft white, conglomeratic; contains brown concretions"

Size classes: macrofossils, mesofossils

Collected by C. Gilmore, J. Reeside, C. H. Sternberg in 1916, 1921-1922; reposited in the USNM

Collection methods: quarrying, surface (float), surface (in situ), mechanical,

• original collection by Gilmore in 1916, followed by main collecting by J. B. Reeside, Jr., June 1921 and additional specimens collected by C. H. Sternberg in 1922; specimens found about 200 ft apart and may represent one individual

Primary reference: C. W. Gilmore. 1921. Discovery of sauropod dinosaur remains in the Upper Cretaceous of New Mexico. Science 54(1395):274 [M. Carrano/M. Carrano/M. Carrano]more details

Purpose of describing collection: biostratigraphic analysis

PaleoDB collection 46992: authorized by Matthew Carrano, entered by Matthew Carrano on 28.01.2005

Creative Commons license: CC BY (attribution)

Taxonomic list

Reptilia
 Testudines -
Testudines indet. Batsch 1788 turtle
incl. Sternberg's #49
 Loricata -
Crocodylia indet. crocodilian
 Ornithischia -
Ankylosauria indet. ankylosaur
"dermal plates of an armored form"
Ceratopsia indet. ceratopsian
teeth
 Theropoda -
Theropoda indet. theropod
teeth; incl. back of skull & pelvis, Sternberg's #50, 51
 Saurischia - Saltasauridae
Alamosaurus sanjuanensis n. gen. n. sp.
Alamosaurus sanjuanensis n. gen. n. sp. Gilmore 1922 saltasaurine
USNM 10486, 10487; UNM FKK-029 (=NMMNH P-29725), NMMNH P-29726