Late Miocene chondrichthyans from Lago Bayano, Panama: Functional diversity, environment and biogeography

Abstract

Abstract.-This newly described chondrichthyan fauna from the late Miocene Chucunaque Formation of Lago Bayano reveals a prolific and highly diverse assemblage from Panama, and one of the richest shark faunas from the Neotropics. Strontium geochronology indicates an age of 10-9.5 Ma for the chonrichthyan-bearing strata. Field efforts resulted in 1429 identifiable specimens comprising at least 31 taxa, of which at least eight are new to the documented fossil record of Panama. With this information an analysis of functional diversity was conducted, indicating ecosystems dominated by generalist species feeding upon a wide range of organisms, from plankton to marine mammals. A probabilistic approach of paleobathymetric estimation suggests a neritic environment. Previous studies based on foraminifera have suggested that the Chucunaque Formation had a greater Pacific Ocean affinity, making this the first Miocene chondrichthyan fauna described from the Pacific shelf of Panama. However, our geographic comparisons show that this fauna has mixed Caribbean and Pacific biogeographic affinities, which likely supports the previously purported connection between chondrichthyan faunas during the late Miocene.

Pre-Messinian ecological diversity of Mediterranean sharks revealed by the study of their dermal denticles

“…based on the assumption of ecological similitude with closely related living taxa, especially in species with extant representatives at family or generic level (e.g., Thies & Müller, 1993;Adnet et al, 2008;Underwood & Schlögl, 2012;Adolfssen & Ward, 2014;Carrillo-Briceño et al, 2016, 2019Perez et al, 2017;. However, conclusions reached by this kind of proxies should be cautiously considered particularly when the ecological extrapolation entails large temporal or phylogenetic distance between the involved species.…”

The transition betweenCarcharocles chubutensisandCarcharocles megalodon(Otodontidae, Chondrichthyes): lateral cusplet loss through time

“…However, this transition is confounded by the morphological variation associated with the ontogeny of C. megalodon, in which juveniles may or may not retain lateral cusplets (Applegate and Espinosa-Arrubarrena, 1996;Pimiento et al, 2010). Further, adult C. megalodon may retain lateral cusplets as a vestigial character (Perez et al, 2017). Thus, although the presence of lateral cusplets is regarded as a definitive character for C. chubutensis, this trait alone is not sufficient for distinguishing C. chubutensis from C. megalodon (Kent, 1994).…”

Integrated Chronology, Flora and Faunas, and Paleoecology of the Alajuela Formation, Late Miocene of Panama

“…13 to 15 Ma. The younger evidence from Alajuela as well as from roughly contemporaneous localities from the Gatun [1] and Chucunaque [62] formations in Panama speak to this debate.…”