El Gramal (Miocene of Mexico)

Also known as Nejapa

Where: Oaxaca, Mexico (16.6° N, 96.1° W: paleocoordinates 17.1° N, 93.3° W)

• coordinate estimated from map

• outcrop-level geographic resolution

When: El Camarón Formation, Barstovian (16.0 - 13.6 Ma)

• formation "is estimated between 200 and 250 m... The fossil mammals occurred in the lower member (usually the lower part), and were collected at several sites [seven shown on map]... from a zone ~30 m thick at the most"; it intertongues with the Yautepec Tuff, dated at 15.0 +/- 0.8 to 16.7+/- 0.71 by K-Ar (Bravo-Cuevas and Ferrusquía-Villafranca 2006)

• member-level stratigraphic resolution

Environment/lithology: terrestrial; poorly lithified, tuffaceous siltstone and poorly lithified, tuffaceous sandstone

• formation is "Friable to moderately indurated tuffaceous siltstone, sandstone and conglomerate; lower part [yielding the fossils] is finer grained and thinly bedded" (Bravo-Cuevas and Ferrusquía-Villafranca 2006)

Size class: macrofossils

Primary reference: I. Ferrusquia-Villafranca. 1990. Biostratigraphy of the Mexican Continental Miocene: Part I, Introduction and the Northwestern and Central Faunas. Part II, The Southeastern (Oaxacan) Faunas. Part III, The Southeasternmost (Chiapasan) Fauna and Concluding Remarks On the Discussed Vertebrate Record. Paleontologia Mexicana 56:1-149 [J. Alroy/J. Alroy/J. Marcot]more details

Purpose of describing collection: general faunal/floral analysis

PaleoDB collection 18724: authorized by John Alroy, entered by John Alroy on 18.02.1993

Creative Commons license: CC BY (attribution)

Taxonomic list

• overlies tuff dated by K-Ar at 14.96 +/- 0.85 Ma
Mammalia
 Perissodactyla - Equidae
Merychippus sp. Leidy 1856 horse
"sensu lato"
 Proboscidea - Gomphotheriidae
Gomphotherium sp. Burmeister 1837 gomphothere
 Ungulata - Camelidae
Camelidae indet. Gray 1821 camel
 Ungulata - Protoceratidae
? Protoceratidae indet. Marsh 1891 protoceratid