Newsletter - Annals of the Brazilian Academy of Sciences
|The present volume of the AABC is the last one to be published for the celebrations of the centenary of the Brazilian Academy of Sciences. Here we have gathered a total of 20 interesting contributions in the field of paleontology. The reader will find the description of new fossil mammals and reptiles, including dinosaurs, pterosaurs and crocodylomorphs; biogeographic studies involving fishes; description of Jurassic conifer-like leaves, parasites in coprolites (ancient animal droppings); osteohistological studies; reviews of the so called Pleistocene megafauna when giant mammals roamed our planet; new geological information on important paleontological deposits; and much more!|
Last but not least, notice the editorial which provides a quick overview of the top fields covered by recent studies on fossils around the world.
Please keep notice that previous editions of the Newsletter are available at the ABC website. All abstracts of the newsletters have been provided by the authors. Since 2000, all papers published by the AABC can be downloaded free of charge at the SciELO site.
We are now inviting you to scroll through the text and click on the title of the article that interests you!
Alexander W. A. Kellner
1- Distributional patterns of Aptian-Albian paleoichthyofauna of Brazil and Africa based on Track analysis
The distributional pattern of Aptian-Albian paleoicthyofauna is poorly known and therefore requires study. Useful tools to interpret these patterns are certain methodologies in Historical Biogeography. In our study, we analyze the Aptian-Albian paleoichthyofauna of Brazil and Africa using the track analysis. From the results (occurrences, individual tracks, generalized tracks and nodes), it was possible to obtain an overview of the biodiversity as well as the distributional pattern of fishes of this interval in Brazil and Africa, considering the events as the break-up of Gondwana, the formation of Atlantic Ocean, and eustatic movements that affected South America and Africa.
2- Holocene history of a lake filling and vegetation dynamics of the Serra Sul dos Carajás, southeast Amazonia
An interdisciplinary study in a lacustrine core of the Serra dos Carajás identified trends in Holocene paleoclimatology. Increase of debris from 9500 to 7000 cal yr BP suggests high weathering of catchment rocks, and deposition into the lake basin under mudflows. In addition, montane savanna and forest formation were already established suggesting predominance of wet climate. However, from 7000 to 3000 cal yr BP, a decline of debris input and forests indicated that lake levels dropped under drier climate. After 3000 cal yr BP, lake and forests acquired their current structures, which suggests return of wetter climate conditions.
3- A new saurolophine hadrosaurid (Dinosauria: Ornithopoda) from the Upper Cretaceous of Shandong, China
The Laiyang Hadrosauroid Fauna, represented by Tsintaosaurus and Tanius, is one of the most important Late Cretaceous dinosaur faunas in China, where Chinese geologists and paleontologists first reported dinosaurs, dinosaur eggs, pterosaurs, insects, and plants. Recently, a new saurolophine dinosaur, Laiyangosaurus youngi (new genus and species) has been described based on several cranial material from the Jingangkou Formation (Upper Cretaceous) of Laiyang. This new taxon is distinguished by four autapomorphies and a unique combination of characters. A phylogenetic analysis suggests that Laiyangosaurus lies in Edmontosaurini, a clade including Edmontosaurus, Shantungosaurus Kundurosaurus and Kerberosaurus.
4- New Crocodyliform specimens from Recôncavo-Tucano Basin (Early Cretaceous) of Bahia, Brazil
Four new crocodyliform specimens are described from the Early Cretaceous Bahia Supergroup (Recôncavo-Tucano Basin), which are an osteoderm, a fibula, a tibia, and some autopodial bones. No further identification besides Mesoeucrocodylia was made due to their fragmentary nature and the reduced number of recognized synapomorphies for more inclusive clades. With exception of the fibula, all other specimens have at least one particular feature, which could not be associated to any recognizable species. Those new specimens described here increase the diversity of Early Cretaceous crocodyliforms from Brazil highlighting the great fossiliferous potential of Recôncavo-Tucano Basin.
5- A review of the Quaternary Scelidotheriinae (Mammalia, Xenarthra, Tardigrada) from the Tarija-Padcaya basin, Bolivia
The subfamily Scelidotheriinae (Mammalia, Xenarthra, Tardigrada) constitutes a particular group of fossil ground sloth that inhabited South America since the middle Miocene to the early Holocene in the current territories of Argentina, Brazil, Bolivia, Peru, Chile, Uruguay, Ecuador and Colombia. More precisely, in Bolivia the Tarija-Padcaya Valley contains one of the most important record of this ground sloths. In this contribution we carry out a taxonomic revision of the Scelidotheriinae present in this area in order to infer the diversity that this group reached during the Pleistocene. Our results indicate that only one species can be recognized as valid, Catonyx tarijensis.
6- Baalsaurus mansillai gen. et sp. nov. a new titanosaurian sauropod (Late Cretaceous) from Neuquén, Patagonia, Argentina
There are more than 70 taxa of titanosaurid sauropods; however, just 10 of them have partial or complete dentaries. Baalsaurus mansillai, gen. et sp. nov. from the Late Cretaceous of Patagonia, Argentina presents a dentary with an unusual rectangular “L” shape with almost all alveoli on the anterior ramus. There are two types of morphology in titanosaur dentaries; “L” shaped or “U” shaped. Baalsaurus mansillai presents a ventrally and anteriorly inclined symphysis and a wide ventral Meckelian groove surrounded by a thin lamina that forms a keel on the ventral border of the dentary.
7- A new protodidelphid (Mammalia, Marsupialia, Didelphimorphia) from the Itaboraí Basin and its implications for the evolution of the Protodidelphidae
The Protodidelphidae is an extinct group of opossum marsupials, which is presently represented only by the extant didelphids. The study describes a new representative of this group, named as Bergqvistherium primigenia. The Protodidelphidae was a generalized and rare group of marsupials before the Paleocene-Eocene Thermal Maximum (PETM), a paleoclimatic event that increased the global temperatures and the extension of the tropical forests. After the PETM, the protodidelphis increased in size, diversity, abundance, and acquired evident adaptations to frugivory. The study supports the PETM as the main environmental event responsible for the evolution of this group.
8- First record of Acanthocephala parasites eggs in coprolites preliminary assigned to Crocodyliformes from the Adamantina Formation (Bauru Group, Upper Cretaceous), São Paulo, Brazil
This paper presents the oldest record of Acanthocephala eggs, dating 80-70 million years, in a coprolite assigned to Crocodyliformes from the Adamantina Formation, recovered in sedimentary rocks of the region of Santo Anastácio Municipality, Southwestern São Paulo State, Brazil. For this, a paleoparasitological investigation was carried out on 53 coprolites. After laboratory processing, the presence of four Acanthocephala eggs, group of intestinal helminths that still parasitize several vertebrates worldwide, could be observed in sample of one of these ichnofossils. Our study inaugurates investigations about Veterinary Paleoparasitology in Crocodylomorpha coprolites from the Bauru Group, Campanian-Maastrichtian, Upper Cretaceous from the Paraná Basin.
9- The Neostratotype of Itapecuru Formation (Lower-Middle Albian) and Its Impact for Mesozoic Stratigraphy of Parnaíba Basin
The research that established the Itapecuru Formation neostratotype of the Mesozoic section of the Parnaíba Basin discovered that the lithological unit is mainly composed of mudrocks, contrary to previous studies. The establishment of their lithofacies and associations allowed them to be interpreted as part of an anastomosed river system, deposited under a semi-arid paleoclimate marked by seasonality. It is important to highlight that the petrographic analysis revealed the frequent occurrence of carbonized phytoclasts, which indicates the existence of significant vegetation near the channels, as well as the periodic occurrence of fires, during part of the deposition of the Itapecuru Formation.
10- Permineralized conifer-like leaves from the Jurassic of Patagonia (Argentina) and its paleoenvironmental implications
Anatomically preserved conifer-like leaves from the Middle Jurassic La Matilde Formation in Patagonia are described. The general foliar habit indicates affinity with the large, multi-veined leaves of the Araucariaceae. Anatomically, the permineralized leaves exhibit xeromorphic foliar features: thick-walled epidermal cells, isobilateral mesophyll with well-developed palisade cells and mechanical tissue. The general leaf anatomy along with sedimentological data may suggest that during the deposition of the La Matilde Formation at the Barda Blanca locality, the parent plant was well adapted to a high light intensity with an adequate quantity of water in the soil increasing the maximum leaf conductance of CO2.
11-Mammal tooth traces in a ferruginous cave in southeastern Brazil and their relevance to cave legal protection
We describe the first occurrence of biogenic alterations made by mammal teeth within an iron formation cave at Minas Gerais state, Brazil. The traces are a product of geophagy or sharpening of teeth. The traces were compared with tooth traces artificially imprinted. This assessment suggested that at least seven extant rodents are potential tracemakers, all of them still living in the area. The age of the traces is unknown, thus its relevance to paleontology is elusive. Yet, regardless of their fossil nature, ichnological features should be considered as an additional value for cave protection, according to the Brazilian legislation.
12- Osteohistology of the silesaurid Sacisaurus agudoensis from southern Brazil (Late Triassic) and implications for growth in early dinosaurs
In this contribution, we provide the first osteohistological description of the limb bones of the silesaurid Sacisaurus agudoensis. The analysis reveals uninterrupted fibrolamellar bone tissue indicating rapid growth. Importantly, we discuss the growth pattern of this taxon and the hypothesis that simpler vascular pattern appears to be typical of all silesaurids studied to date which indicates relatively slower growth rates compared to Dinosauria. Given that few silesaurids taxa have been analyzed histologically, our study helps to fills the knowledge gap on dinosauriform growth, which is an important contribution towards understanding the acquisition of dinosaur osteohistological characteristics and hence growth patterns.
13- New material of Sinopterus (Pterosauria, Tapejaridae) from the Early Cretaceous Jehol Biota of China
Tapejaridae is a clade of toothless pterosaurs typically characterized by a large nasoantorbital fenestra and a premaxillary crest that extends from the anterior to the posterior part of the skull. Sinopterus dongi was the first reported Chinese tapejarid. Another genus “Huaxiapterus” was described, but it was later on determined that “Huaxiapterus” is in fact an invalid name. Here, we report on a new juvenile specimen of Sinopterus atavismus from the Jiufotang Formation of western Liaoning, China, and revise the diagnosis of this species.
14- An overview of the appendicular skeletal anatomy of South American titanosaurian sauropods, with definition of a newly recognized clade
Sauropods were long-necked plant-eating dinosaurs that exceeded all other land-living backboned animals in maximum body size. Representatives of the sauropod subgroup Titanosauria were the most abundant and diverse herbivorous dinosaurs in the Southern Hemisphere landmasses during the latter part of the Cretaceous Period, in the few tens of millions of years prior to the mass extinction that wiped out non-avian dinosaurs 66 million years ago. In the present paper, Bernardo J. González Riga and colleagues present an extensive study of the shoulder, hip, and limb bones of South American titanosaurs, and recognize the presence of a newly-identified titanosaur lineage that they name Colossosauria (meaning “giant dinosaurs”). Colossosaurs include the heaviest terrestrial animals known to date (with maximum masses reaching as much as 50–70 tons), such as the Argentinean forms Argentinosaurus, Patagotitan, and Notocolossus, the latter boasting a powerfully-built humerus 1.76 m in length. The extreme body size of the largest titanosaurs poses considerable challenges for understanding the behavior and locomotion of these enormous animals.
15- Morphology of the megaspore Lagenoisporites magnus (Chi and Hills 1976) Candilier et al. (1982), from the Carboniferous (lower Mississippian: mid-upper Tournaisian) of Bolivia
Megaspores assigned to Lagenoisporites magnus, from mid-upper Tournaisian of Bolivia, were studied using light, fluorescence and scanning electron microscopy. Megaspores were laterally compressed and presented a spherical body, bearing complex processes, and a proximal hologula with verrucae. These megaspores were assigned to the Lepidocarpaceae (arborescent lycopsids), as in section view, exospore structure presented a three-dimensional network of fused elements. Due to its similarity to the Isoetes structure, it is evident that megaspores structure has remained intact inside the heterosporous lycopsids. Therefore; the L. magnus structure not only would confirm its affinity with Lycophyta fossils but also with the living ones.
16- A dinosaur ilium from the Late Triassic of Brazil with comments on key-character supporting Saturnaliinae
A dinosaur specimen from Brazilian Triassic rocks with the oldest dinosaur records worldwide reinforces the idea that early dinosaurs experienced considerable variation along its development stages. Thus, when these issues are overlooked, specimens at different development stages may be misidentified as distinct taxa. Therefore, the specimen led us to identify a possible development pathway regarding morphological variations present in the pelvic girdle of several early dinosaurs, especially sauropodomorphs, members of the lineage that would give rise to the largest terrestrial vertebrates the planet has ever witnessed.
17- A new toothless pterosaur (Pterodactyloidea) from Southern Brazil with insights into the paleoecology of a Cretaceous desert
A new extinct flying reptile is described. Named Keresdrakon vilsoni, the new species was recovered from Southern Brazil from a deposit that several million of years ago represented an oasis in a desert. More important than revealing the new species, the study shows the first direct evidence of sympatry in pterosaurs: two species occurred in the same geographical region each specializing on different prey items. Also, a dinosaur co-occurred in the same area, allowing a glimpse into the paleoecology of an ancient desert. Keresdrakon most likely had a solitary behavior and was feeding on small pterosaurs or scavenged carcasses of dinosaurs.
18- Osteoderm microstructure of Riostegotherium yanei, the oldest Xenarthra
Riostegotherium yanei, from Itaboraí Basin, Brazil, is the oldest Xenarthra so far (Early Eocene). It was defined based on isolated osteoderms, and this paper aims to describe them from the perspective of histology and micro-CT approaches, expanding the available data on cingulate osteoderm microstructure. The osteoderms have a three-layered structure composed of two layers of non-Haversian compact bone enclosing a central layer of primary and secondary osteons. This internal organization is distinct from other Astegotheriini of comparable age, but similar to the extant Dasypus. The 3D reconstruction of revealed two patterns of internal organization, one with larger cavities and the other with smaller, more numerous, and more interconnected cavities.
19- Pterodactyloid pterosaur bones from Cretaceous deposits of the Antarctic Peninsula
Extinct vertebrate remains from Antarctica are comparatively rare and quite hard to find due to the climatic conditions that makes prospection for fossils difficult. The expeditions carried out by the PALEOANTAR project have recovered hundreds of isolated bones in several sites of the Antarctic Peninsula. Here we report the first pterosaur elements found in Late Cretaceous deposits of the James Ross and Vega islands which, despite their incompleteness, show that large flying reptiles were widespread through all parts of the planet, including the Antarctic Peninsula.
20-The Evolution of Pneumatic Foramina in Pterosaur Vertebrae
A cladistical analysis was performed after the incorporation of eight new characters referring to the position of pneumatic foramina present in the vertebral column of pterosaurs, which not explored in data matrix previously suggested. Posteriorly, these new characters were mapped in the strict consensus tree, this is significant because the mapping has potential to verify possible homologies on the skeletal pneumatization in pterosaurs. According to our analysis, the mapping identified that most of the added characters evolved independently in several lineages, and just in two of the eight characters appeared once in the evolution of the clade.
|All abstracts of the publications were provided by the respective authors.|