Neogene Caribbean elasmobranchs: Diversity, paleoecology and paleoenvironmental significance of the Cocinetas Basin assemblage (Guajira Peninsula, Colombia)

Abstract

The Cocinetas Basin is located on the eastern flank of the Guajira Peninsula, northern Colombia (southern Caribbean). During the late Oligocene through the Pliocene, much of the basin was submerged. The extensive deposits in this area suggest a transition from a shallow marine to a fluvio-deltaic system, with a rich record of invertebrate and vertebrate fauna. The elasmobranch assemblages of the early Miocene to the late Pliocene succession in the Cocinetas Basin (Jimol, Castilletes and Ware formations, as well as the Patsúa Valley) are described for the first time. The assemblages include at least 30 taxa of sharks (Squaliformes, Pristiophoriformes, Orectolobiformes, Lamniformes and Carcharhiniformes) and batoids (Rhinopristiformes and Myliobatiformes), of which 24 taxa are reported from the Colombian Neogene for the first time. Paleoecological interpretations are based on the feeding ecology and on estimates of the paleohydrology (relative salinity, temperature) using stable isotope compositions of oxygen in the bioapatite of shark teeth. The isotopic composition of the studied specimens corroborates paleoenvironmental settings for the studied units that were previously estimated based on the sedimentology and biology of the taxa. These Neogene elasmobranch assemblages from the Cocinetas Basin provide new insights into the diversity the sharks and rays inhabiting the coastal and estuarine environments of the northwestern margin of South America, both during the existence of the gateway between the Atlantic and Pacific oceans and following its closure.

A fossil fish assemblage from the middle Miocene of the Cocinetas Basin, northern Colombia

“…2016; Aguilera et al . 2017; Carrillo-Briceño et al . 2019); in contrast, freshwater fishes remains largely unreported in these assemblages (but see Aguilera et al .…”

Shark fossil diversity (Squalomorphii, Squatinomorphii, and Galeomorphii) from the Langhian of Brielas (Lower Tagus Basin, Portugal)

“…18), and Godfrey (2018, fig. 2.22n–p), more so than the ones of C. perezi figured by Carrillo‐Briceño et al (2019, fig. 5v,w), Godfrey (2018, fig.…”

“…The connections between the cutting edges and the respective heels on the studied teeth are angular as in C. priscus figured by Carrillo‐Briceño et al (2019, fig. 5x–z'), Antunes et al (1981, plate 2, fig.…”

A stem delphinidan from the Caribbean region of Venezuela

“…Marine species diversity of this region is mostly endemic and rather new due to the fairly recent closure of the Central American Seaway during the Miocene; and the subsequent rise of the Panama land isthmus during the Pliocene (Jaramillo 2018 ; Stange et al 2018 ). The Neogene fossil record of marine vertebrates in the Caribbean is mostly represented by abundant chondrichthyan and bony fish remains (Aguilera 2010 ; Laurito and Valerio 2011 ; Carrillo-Briceño et al 2015a , b , 2019 ; Aguilera et al 2016 ). In contrast, cetaceans have a scarce and restricted record on the Caribbean region, which includes a few depositional sequences from the Miocene of both Colombia (Castilletes Fm.)…”