Bones, carnivores, and grassland fires. Actualistic taphonomy of faunal assemblages from two caves in Central Argentina and its implication for the fossil record

2021 ◽  
pp. 1-14
Author(s):  
M. Paula Weihmüller ◽  
Camila Brizuela ◽  
Julián Mignino ◽  
Andrés I. Robledo
2015 ◽  
Vol 112 (37) ◽  
pp. 11467-11472 ◽  
Author(s):  
Thure E. Cerling ◽  
Samuel A. Andanje ◽  
Scott A. Blumenthal ◽  
Francis H. Brown ◽  
Kendra L. Chritz ◽  
...  

A large stable isotope dataset from East and Central Africa from ca. 30 regional collection sites that range from forest to grassland shows that most extant East and Central African large herbivore taxa have diets dominated by C4 grazing or C3 browsing. Comparison with the fossil record shows that faunal assemblages from ca. 4.1–2.35 Ma in the Turkana Basin had a greater diversity of C3–C4 mixed feeding taxa than is presently found in modern East and Central African environments. In contrast, the period from 2.35 to 1.0 Ma had more C4-grazing taxa, especially nonruminant C4-grazing taxa, than are found in modern environments in East and Central Africa. Many nonbovid C4 grazers became extinct in Africa, notably the suid Notochoerus, the hipparion equid Eurygnathohippus, the giraffid Sivatherium, and the elephantid Elephas. Other important nonruminant C4-grazing taxa switched to browsing, including suids in the lineage Kolpochoerus-Hylochoerus and the elephant Loxodonta. Many modern herbivore taxa in Africa have diets that differ significantly from their fossil relatives. Elephants and tragelaphin bovids are two groups often used for paleoecological insight, yet their fossil diets were very different from their modern closest relatives; therefore, their taxonomic presence in a fossil assemblage does not indicate they had a similar ecological function in the past as they do at present. Overall, we find ecological assemblages of C3-browsing, C3–C4-mixed feeding, and C4-grazing taxa in the Turkana Basin fossil record that are different from any modern ecosystem in East or Central Africa.


2018 ◽  
Author(s):  
Fatima Mendoza Belmontes ◽  
Ricardo N Melchor ◽  
Luis N Piacentini

Pavocosa sp. (Lycosidae) burrows found in an open sparsely vegetated area on the edge of the saline lake the “Gran Salitral”, in central Argentina, are described. Burrows were studied by capturing the occupant and casting them with dental plaster. The hosting sediments and vegetation were also characterized. Inhabited Pavocosa sp. burrows display distinctive features as open, cylindrical, nearly vertical, silk lined shafts about 120 mm long, subcircular entrances, a gradual downward widening, and a particularly distinctive surface ornamentation in the form of sets of two linear parallel marks at a high angle to the burrow axis. Instead, casts of vacated Pavocosa sp. burrows showed some disturbances caused either by the reoccupation by another organism or by predation of the dweller. Two morphologies are related to reoccupation of burrows: those with a structure in form of an "umbrella” and another with smaller excavations at the bottom of the burrow. Predation by armadillos produces funnel-shaped burrows. Both active and abandoned Pavocosa sp. burrow casts are compared with existing ichnogenera and its distinction is discussed. It is argued that key features like the presence of a neck, a downward widening and the surface texture will allow recognition of wolf spider burrows in the fossil record. Fossil wolf spiders are recorded since the Paleogene (possibly Late Cretaceous), so Cenozoic continental rocks can contain wolf spider burrows awaiting recognition. In addition, the particular distribution of Pavocosa sp. in saline lakes may imply that this type of burrows are linked to saline environments.


2019 ◽  
Vol 47 (1) ◽  
pp. 519-553 ◽  
Author(s):  
David W. Krause ◽  
Joseph J.W. Sertich ◽  
Patrick M. O'Connor ◽  
Kristina Curry Rogers ◽  
Raymond R. Rogers

The Mesozoic plate tectonic and paleogeographic history of Gondwana had a profound effect on the distribution of terrestrial vertebrates. As the supercontinent fragmented into a series of large landmasses (South America, Africa-Arabia, Antarctica, Australia, New Zealand, the Indian subcontinent, and Madagascar), particularly during the Late Jurassic and Cretaceous, its terrestrial vertebrates became progressively isolated, evolving into unique faunal assemblages. We focus on four clades that, during the Mesozoic, had relatively low ability for dispersal across oceanic barriers—crocodyliforms, sauropod dinosaurs, nonavian theropod dinosaurs, and mammals. Their distributions reveal patterns that are critically important in evaluating various biogeographic hypotheses, several of which have been informed by recent discoveries from the Late Cretaceous of Madagascar. We also examine the effects of lingering, intermittent connections, or reconnections, of Gondwanan landmasses with Laurasia (through the Caribbean, Mediterranean, and Himalayan regions) on the distributions of different clades. ▪ This article reviews the biogeographic history of terrestrial vertebrates from the Mesozoic of the southern supercontinent Gondwana. ▪ Relatively large, terrestrial animals—including crocodyliforms, sauropod and nonavian theropod dinosaurs, and mammals—are the focus of this review. ▪ Most patterns related to vicariance occurred during the Late Jurassic and Cretaceous, the intervals of most active Gondwanan fragmentation. ▪ Recent discoveries of vertebrates from the Late Cretaceous of Madagascar have played a key role in formulating and testing various biogeographic hypotheses.


2020 ◽  
Vol 47 (1) ◽  
pp. 162
Author(s):  
Gabriel Andrés Casal ◽  
Patricia Vallati ◽  
Lucio Manuel Ibiricu ◽  
Andrea De Sosa Tomas ◽  
Nicolás Foix ◽  
...  

The presence of stromatolites from Cretaceous outcrops at the headwaters of the río Chico locality in the Golfo San Jorge Basin is reported for the first time. They are present in the uppermost part of the Lago Colhué Huapi Formation (Coniacian-Maastrichtian) of the Chubut Group. The presence of, up to now, four structures interpreted as stromatolites in this locality are not only important because it is the first record in the basin, but because it contributes to the knowledge of these bioconstructions in continental environments. The stromatolite called E1, which is characterized and discussed in detail, is associated with an abundant and diverse fossil record represented by palynomorphs, fragments of silicified trunks, dinosaur remains and eggshells. The study, integrated mainly with the recorded pollen and spores, is important for paleoenvironmental interpretations of the site and contributes to the paleoecological and paleoclimatic understanding of the most modern stratigraphic interval of the Chubut Group.


PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5054
Author(s):  
Fatima Mendoza Belmontes ◽  
Ricardo N. Melchor ◽  
Luis N. Piacentini

Pavocosasp. (Lycosidae) burrows found in an open sparsely vegetated area on the edge of the Gran Salitral saline lake, in central Argentina, are described. Burrows were studied by capturing the occupant and casting them with dental plaster. The hosting sediments and vegetation were also characterized. InhabitedPavocosasp. burrows display distinctive features as open, cylindrical, nearly vertical, silk lined shafts about 120 mm long, subcircular entrances, a gradual downward widening, and a particularly distinctive surface ornamentation in the form of sets of two linear parallel marks at a high angle to the burrow axis. Instead, casts of vacatedPavocosasp.burrows showed some disturbances caused either by the reoccupation by another organism or by predation of the dweller. Two morphologies are related to reoccupation of burrows: those with a structure in form of an “umbrella” and another with smaller excavations at the bottom of the burrow. Predation by small mammals produces funnel-shaped burrows. Both active and abandonedPavocosasp. burrow casts are compared with existing ichnogenera and inorganic sedimentary structures, highlighting its distinction. It is argued that key features like the presence of a neck, a downward widening and the described surface texture will allow recognition of wolf spider burrows in the fossil record. However, the putative spider burrows described in the literature either lack the necessary preservational quality or do not show ornamentation similar to the modern wolf spider burrows. Fossil wolf spiders are recorded since the Paleogene (possibly Late Cretaceous), therefore Cenozoic continental rocks can contain wolf spider burrows awaiting recognition. In addition, the particular distribution ofPavocosasp. in saline lakes may imply that this type of burrow is linked to saline environments.


2018 ◽  
Vol 115 (1/2) ◽  
Author(s):  
Charles W. Helm ◽  
Hayley C. Cawthra ◽  
Jan C. de Vynck ◽  
Martin G. Lockley ◽  
Richard T. McCrea ◽  
...  

East of Still Bay on the Cape south coast of South Africa lies a rugged, remote stretch of sea cliffs that expose Late Pleistocene aeolianites. A zone of dense concentration of fossil tracks occurs within this area. Two large rocks, which we call Roberts Rock and Megafauna Rock, were identified ~400 metres apart. These rocks contained a variety of trackways, individual tracks, burrow traces and invertebrate trace fossils on multiple bedding planes. Both rocks were found ex situ, but their context could be determined. Roberts Rock has subsequently slid into the ocean, and Megafauna Rock lies at the base of a coastal cliff. Probable trackmakers include elephant, long-horned buffalo, giant Cape horse, rhinoceros, medium and small artiodactyls, golden mole, birds and invertebrates. Dating studies at an adjacent site, which is comparable to the stratigraphy described here, indicate that both rocks were most likely deposited in Marine Isotope Stage 5e (~128–116 ka). Analysis and description of these tracksites confirms the potential of ichnology to complement the skeletal fossil record and to enhance the understanding of Pleistocene life in southern Africa. The ephemeral nature of such tracksites makes repeated visits to this coastline desirable, both to monitor the fate of known sites and to search for newly exposed trace fossil surfaces. Significance: • Roberts Rock and Megafauna Rock are two remarkable fossil tracksites on the Cape south coast, which contain tracks of four members of the Late Pleistocene megafauna. They provide a glimpse of Pleistocene dune life and suggest an area teeming with large mammals. • These tracks were made on dune surfaces near an interface between the grassland of the Palaeo-Agulhas Plain and the inland Fynbos–Strandveld–Renosterveld. Faunal assemblages from both vegetation zones might therefore be recorded. • The trace fossil record and body fossil record both have inherent biases, but have the potential to independently provide complementary information on palaeofaunal composition. • The two rocks have provided the first South African records of fossil elephant tracks (as first described by Dave Roberts and colleagues in 2008), the first rhinoceros track and the first extinct giant Cape horse track, and track evidence of the extinct long-horned buffalo. • Roberts Rock has slumped into the ocean, and it provides an example of the fate of many exposed tracksites. Conversely, new sites frequently become exposed. This scenario stresses the need for regular ichnological surveys along this track-rich coastline to monitor existing sites and to search for new sites.


Author(s):  
Nicholas C. Fraser ◽  
Hans-Dieter Sues

ABSTRACTThe first appearance of dinosaurs during the early Late Triassic coincided with marked faunal changes in terrestrial ecosystems. Most of the major groups of extant tetrapods (or their proximate sister-taxa), including mammaliaforms, crocodyliform archosaurs, lepidosaurs and turtles, also first appeared in the fossil record during the Late Triassic. On the other hand, a number of Palaeozoic ‘holdovers’, such as procolophonid parareptiles, dicynodont therapsids and many groups of temnospondyls, vanished near or at the end of the Triassic. The tempo and mode of this faunal turnover have long been debated, but there has been growing acceptance of a rather sudden event, although the precise dating of such an event remains controversial. However, new discoveries have cast doubt on this assumption. The persistence of non-dinosaurian dinosauromorphs alongside dinosaurs well into Norian times hints at a more protracted turnover. New data on Triassic insect assemblages indicate that turnover among insects may also have been more protracted and possibly not co-incident with the faunal changes among tetrapods. Future work directed toward improved absolute age assessments for major faunal assemblages will be critical for a better understanding of the transition from therapsid-dominated to dinosaur-dominated communities during the early Mesozoic.


2018 ◽  
Author(s):  
Fatima Mendoza Belmontes ◽  
Ricardo N Melchor ◽  
Luis N Piacentini

Pavocosa sp. (Lycosidae) burrows found in an open sparsely vegetated area on the edge of the saline lake the “Gran Salitral”, in central Argentina, are described. Burrows were studied by capturing the occupant and casting them with dental plaster. The hosting sediments and vegetation were also characterized. Inhabited Pavocosa sp. burrows display distinctive features as open, cylindrical, nearly vertical, silk lined shafts about 120 mm long, subcircular entrances, a gradual downward widening, and a particularly distinctive surface ornamentation in the form of sets of two linear parallel marks at a high angle to the burrow axis. Instead, casts of vacated Pavocosa sp. burrows showed some disturbances caused either by the reoccupation by another organism or by predation of the dweller. Two morphologies are related to reoccupation of burrows: those with a structure in form of an "umbrella” and another with smaller excavations at the bottom of the burrow. Predation by armadillos produces funnel-shaped burrows. Both active and abandoned Pavocosa sp. burrow casts are compared with existing ichnogenera and its distinction is discussed. It is argued that key features like the presence of a neck, a downward widening and the surface texture will allow recognition of wolf spider burrows in the fossil record. Fossil wolf spiders are recorded since the Paleogene (possibly Late Cretaceous), so Cenozoic continental rocks can contain wolf spider burrows awaiting recognition. In addition, the particular distribution of Pavocosa sp. in saline lakes may imply that this type of burrows are linked to saline environments.


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