Diversity and preservation of Pleistocene tetrapods from caves of southwestern Bahia, Brazil

Abstract

The study of two caves from the Serra do Ramalho region is here presented, this is one of the most important karstic areas in Brazil. A taxonomic analysis revealed 29 taxa including Xenarthra, Cetartiodactyla and Carnivora, ranging from Late Pleistocene to Early Holocene. Taphonomic studies reveal taphocoenosis consisting mainly of complete elements, without significant transportation, but also of transported elements, composing spatial-mixed, predominantly in situ-preserved assemblages. The predominance of Xenarthrans found within the caves is probably biased by a taphonomic pattern since these animals would have life habits related to cave environments, therefore with higher chances of preservation. There is evidence of accidental death of the scelidotheriines in Lapa dos Peixes cave, where entrapment of the animals during one or more events of river flooding is pointed as a hypothesis. Deposition took place within different periods of dry and humid climate incorporating bones in clastic and chemical deposits. Cycles of sedimentary deposition and reworking (erosion) may have acted in generating complex and overlapping depositional patterns with time averaging. During depositional phase, while the cave environment was occupied rather by Xenarthrans, parts of other animals were transported in the scope of fluvial systems and gravity loads, as well as by accidental falling or scavengers. The sedimentary deposits are currently being eroded by rain runoff in both caves, causing the reallocation of finer sediments to deeper conduits but the fossils keep close to their original location. This process is exposing a large amount of fossils, allowing extensive sampling which would be impossible with active excavations, since it would require an excessively longer time and damages to the caves.

A new species of Chaimowiczia from the karstic Serra do Ramalho plateau, Brazil (Oniscidea, Synocheta, Styloniscidae)

“…The local climate is "Aw", according to Köppen's climate classification system, with dry winter and an average annual rainfall of 640 mm³ (Alvares et al 2013). The local karst presents a strongly undulating relief, with epigean drainages typically ephemeral, forming deep-steep incisions (da Silva et al 2019). The area presents more than 180 known caves, some of them among the biggest caves recorded for Brazil, many with more than 5 km in extension (Auler et al 2001).…”

First cancer in an extinct Quaternary non-human mammal

“…The individual is assigned to the Pleistocene ground sloth Nothrotherium maquinense, and its remains were collected at Lapa dos Peixes I (13°49′ 22,08″ S; 43°57′25,20″ W, Carinhanha municipality, southwestern Bahia state, Brazil). This cave is located at Serra do Ramalho plateau, an outstanding karstic limestone outcrop of Brazil (see da Silva et al 2019 for more details). All specimens are housed in the palaeontological collection of Museu de Ciências da Terra (MCTer), Serviço Geológico do Brasil -CPRM, Rio de Janeiro, Brazil.…”

“…The taxonomic attribution of the specimen studied here was provided by da Silva et al (2019), and was based on characteristics described by Paula-Couto (1959) and Cartelle and Fonseca (1983) such as: the mandible has three molariforms of nearly quadrangular shape in occlusal view, in which labial and mesial faces are longer; the femurs are large and anteroposteriorly flattened, with distal articular facets separated; and the tibia is curved and robust at the extremities, with no procnemial crest.…”

Osteohistological analysis and preservation stage of Coendou magnus Lund, 1839 (Rodentia, Erethizontidae) fossils recovered at Toca da Barriguda Cave, Northeastern Brazil

“…Pleistocene vertebrate fossils are commonly found in different types of fossiliferous deposits in northeastern Brazil. Amid these deposits, a large number of fossils found in carbonate caves in the Chapada Diamantina region, State of Bahia, Brazil, have drawn considerable attention (Lessa et al, 1998;Castro et al, 2014;Dantas et al, 2019Dantas et al, , 2020Silva et al, 2019;Eltink et al, 2020). Many of these fossils are representative of extant mammals, such as Tamandua tetradactyla Linnaeus, 1758, Panthera onca Linnaeus, 1758, Leopardus pardalis (Linnaeus, 1758), and Dicotyles tajacu Linnaeus, 1758 (Eltink et al, 2020;Alves-Silva et al, 2023), whereas others are from extinct animals, such as giant sloths Catonyx cuvieri (Lund, 1839), Nothrotherium maquinense (Lund, 1839), and Eremotherium laurillardi Lund, 1839 (Vasconcelos et al, 2016;Dantas et al, 2019).…”