Continental trace fossils from the Miocene-Pliocene Río Negro Formation (Río Negro and Buenos Aires provinces), Argentina

RICARDO NESTOR MELCHOR; MARIANO PEREZ; ALDO MARTÍN UMAZANO

SLIC2013 Postsymposium Fieldtrip Guidebook

Universidad Nacional de La Pampa - INCITAP

Lugar: Santa Rosa; Año: 2013; p. 35 - 48

The vertebrate ichnofauna of the Neogene Río Negro Formation is composed of abundant mammal and bird footprints, and vertebrate burrows. This ichnofauna has been extensively recorded from sea cliff exposures located south of the mouth of the Negro river, and also on the left margin of that river downstream of Carmen de Patagones city. One of the remarkable aspects of this ichnofauna is the presence of trackways of large mammals, including those named as Megatherichnum oportoi Casamiquela 1974, which provides evidence for bipedal locomotion in Megatherioidea. We will visit the site of these trackways in the morning of day 2. This ichnofauna also includes Mylontidichnum (medium-sized ground sloth tracks), Porcellusignum (Hydrocoeridae footprints), ungulate footprints, and probable Thylacosmilidae footprints. The avian tracks are also diverse including, a trackway assigned to a Phorusrhacidae (terror birds), Phoenicopterichnum (flamingo-like footprints) and heron-like tracks. Burrows of vertebrate origin have been recently recognized as Nagtuichnus meuleni Melchor et al. 2012, which was assigned to pink fairy armadillos. In addition to vertebrate tracks, there are many invertebrate and plant trace fossils, some of them will be recognized during the trip. This part of the fieldtrip starts immediately after Stop 5 at El Faro beach (see previous chapter).