Asuncion (Miocene to of Mexico)

Also known as Arroyo Tiburón, Arroyo Las Chivas; CAS 945, 960; IGM 126, 237, 2521, 2523, 2524, 2525, 2527, 2528, 2529, 2531; LACM 3892

Where: Baja California Sur, Mexico (27.1° N, 114.3° W: paleocoordinates 26.6° N, 110.4° W)

• coordinate estimated from map

When: Torgugas Formation, Langhian to Langhian (16.0 - 7.2 Ma)

• near the base of the Tortugas Formation

•The geology around the type locality was mapped by Throughton [12] who referred to the sediments exposed here as the Tortugas Formation. The age of the Tortugas Fm. seems to be relatively broad across its distribution, ranging over mid–late Miocene [15]. The exposure at Arroyo La Chiva (Arroyo Tiburón) was dated by Pérez-Guzmán [16] to between 15.7 and 7.8Ma, based on the occurrence of radiolarians of the Dorcadospyris alata and Diartus hughesi zones [17]. Moreno-Ruiz & Carreño [14] studied the diatomites below the overlying Almejas Fm. in this area, and report diatoms belonging to the Denticulopsis hustedtii-D. lauta Subzone D, which gives it an age between 9.9 and 9.2 Ma [18]. The bone-bearing units are towards the lower part of the formation [12,13], therefore we restrict the range for UABC FCM 0072 and LACM 60914 to between 15.7 and 9.2Ma (Langhian–mid Tortonian: mid to late Miocene)

• formation-level stratigraphic resolution

Environment/lithology: marine; conglomerate

• pebble bed

Size class: macrofossils

Primary reference: L. G. Barnes. 1998. The sequence of fossil marine mammal assemblages in Mexico. Avances en investigacion 1 [M. Uhen/M. Uhen/M. Uhen]more details

Purpose of describing collection: general faunal/floral analysis

PaleoDB collection 57778: authorized by Mark Uhen, entered by Mark Uhen on 22.12.2005

Creative Commons license: CC BY (attribution)

Taxonomic list

• Arroyo Las Chivas Local Fauna
Mammalia
 Perissodactyla -
Desmostylia indet. Reinhart 1953 desmostylian
 Perissodactyla - Paleoparadoxiidae
aff. Paleoparadoxia sp. Reinhart 1959 desmostylian
 Carnivora - Odobenidae
Nanodobenus arandai n. gen. n. sp.2 Velez and Salinas-Márquez 2018 walrus
aff. Neotherium sp. Kellogg 1931 walrus
 Carnivora -
Imagotariinae indet. Mitchell 1968 pinniped
 Carnivora - Desmatophocidae
aff. Allodesmus sp. Kellogg 1922 pinniped
 Sirenia - Dugongidae
Dugongidae indet. Gray 1821 dugong
 Mysticeti -
aff. Parietobalaena sp. Kellogg 1924 whale
 Mysticeti - Cetotheriidae
Cetotheriidae indet. Brandt 1872 whale
sp. A, B, C
aff. Nannocetus sp.1 Kellogg 1929 whale
 Odontoceti - Physeteridae
Physeteridae indet. Gray 1821 sperm whale
 Odontoceti -
Liolithax ? kernensis Kellogg 1931 toothed whale
 Odontoceti - Kentriodontidae
Kentriodontidae indet. Slijper 1936 toothed whale