Rio Yuka assemblage (Miocene of Venezuela)

Where: Portugesa, Venezuela (9.0° N, 70.1° W: paleocoordinates 8.2° N, 66.7° W)

• coordinate estimated from map

When: Santacrucian to Friasian mammal zone, Rio Yuka Formation, Burdigalian (20.4 - 16.0 Ma)

Environment/lithology: marine; sandstone

• In agreement with the vertebrate assemblage here described, the Rio Yuca Formation is usually considered as a molasse unit that was deposited during the initial phases of the Andean uplift in continental and tropical environments. Adinotherium suggests the presence of open habitats, while the peltephilid is indicative of a mixture of open and relatively closed environments. The presence of the two freshwater fishes, plus the giant Purussaurus, indicates the presence of rivers or lakes in the vicinity of the study area.
• The Rı ́o Yuca Formation outcrops (Fig. 1(c)) commonly consist of violet, yellow and light red paleosoils, with decameter- thick layers of lenticular sandstones. The sandstones represent repeated graded cycles in a single package, with gravel at the base. At the top of one of these lenticular packages were localized concentrations of bone fragments herein described, plus phosphatized coprolites and a centimeter-thick rhizoconcretion horizon. Fragments of turtle carapace and cetacean vertebrae were also recovered in the lower beds of the Rio Yuca Formation.

Size class: macrofossils

Collection methods: IVIC-P, Coleccion de Paleontologia, Instituto Venezolano de Investigaciones Cientificas, Caracas, Venezuela.

Primary reference: A. D. Rincon, A. Solorzano, O. Macsotay, H. G. McDonald, and M. Nunez-Flores. 2016. A new Miocene vertebrate assemblage from the Rio Yuca Formation (Venezuela) and the northernmost record of typical Miocene mammals of high latitude (Patagonian) affinities in South America. Geobios 49:395-405 [E. Vlachos/E. Vlachos]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 190535: authorized by Evangelos Vlachos, entered by Evangelos Vlachos on 10.12.2017

Creative Commons license: CC BY (attribution)

Taxonomic list

Platysilurus sp.
IVIC-P-2911; partial skull with the anterior margin broken (lacking parasphenoid and lateral ethmoids), and terminus of the supraoccipital posterior process broken
Peltephilidae indet.
nov. gen, nov. sp.? IVIC-P-2910; one fixed osteoderm
 Siluriformes - Pimelodidae
Phractocephalus sp. Spix and Agassiz 1829 cajaro
IVIC-P-2912; partial sphenotic
 Testudinata -
Testudinata indet. Oppel 1811 turtle
various plates, not described in detail
 Crocodylia - Alligatoridae
cf. Purussaurus sp. Barbosa Rodrigues 1892 crocodilian
IVIC-P-2909; isolated tooth
 Notoungulata - Toxodontidae
cf. Adinotherium sp. Ameghino 1887 notoungulate
IVIC-P-2913; fragment of isolated upper molar (probably left M1) with the posterior part eroded (posterior portion of the ectoloph broken)