| 1. |
- Bajdek, Piotr, et al.
(författare)
-
Microbiota and food residues including possible evidence of pre-mammalian hair in Upper Permian coprolites from Russia
- 2016
-
Ingår i: Lethaia. - : Scandinavian University Press / Universitetsforlaget AS. - 0024-1164 .- 1502-3931. ; 49:4, s. 455-477
-
Tidskriftsartikel (refereegranskat)abstract
- Coprolites (fossil faeces) provide direct evidence on the diet of its producer and unique insights on ancient food webs and ecosystems. We describe the contents of seven coprolites, collected from the Late Permian Vyazniki site of the European part of Russia. Two coprolite morphotypes (A, B) contain remains of putative bacteria, cyanobacteria, fungi, protists, invertebrate eggs, arthropod elements, undigested bone and tooth fragments, fish scales and elongated hair-like structures with hollow interiors. Content, size and shape of the coprolites together with the associated body fossil record suggest that the most probable scat-producers were carnivorous tetrapods; the bone-rich morphotype A reveals short food retention time and a fast metabolism and is therefore assigned to therapsid carnivores whereas morphotype B with rarer and degraded bones are assigned to archosauromorphs or other non-therapsid carnivores. The general coprolite matrix contains abundant micron-sized spheres and thin-walled vesicles which are interpreted as oxide and phosphatic pseudomorphs after microbial cells. From analyses of the undigested bones, we infer that they represent remains of actinopterygian fish, a therapsid and unrecognizable parts of amphibians and/or reptiles. Additionally, hair-like structures found in one coprolite specimen occur as diagenetically altered (oxide-replaced) structures and moulds (or partly as pseudomorphs) in a microcrystalline carbonate-fluoride-bearing calcium phosphate. This suggests that the latest Permian therapsids probably were equipped with hair-like integument or hairsuit. If true, this is by far the oldest evidence of this mammalian character in the stem group of mammals.
|
|
| 2. |
- Bajdek, Piotr, et al.
(författare)
-
Residues from the Upper Permian carnivore coprolites from Vyazniki in Russia - key questions in reconstruction of feeding habits
- 2017
-
Ingår i: Palaeogeography, Palaeoclimatology, Palaeoecology. - : ELSEVIER SCIENCE BV. - 0031-0182 .- 1872-616X. ; 482, s. 70-82
-
Tidskriftsartikel (refereegranskat)abstract
- Residues of twenty-five coprolite fragments collected from the Upper Permian of Vyazniki (European Russia) were studied in detail. The phosphatic composition, general shape and size, and bone inclusions of these specimens indicate that medium to large-sized carnivores, such as therocephalian therapsids or early archosauriforms, were the most likely coprolite producers. The contents of the examined fossils (i.e. Scale, bone and tooth fragments, mineral grains, and microbial structures) do not differ significantly among the samples, implying fairly comparable feeding habits of their producers. Fragments of large tooth crowns in two of the analyzed samples imply that either (1) the coprolite producer swallowed the cranial elements of its prey or (2) the coprolite producer broke and swallowed its own tooth while feeding (such tooth damage is known in archosaurs that have tooth replacement, e.g. crocodiles and dinosaurs). Indeed, the most complete tooth fragment in these fossils is serrated, most likely belonging to an early archosauriform known from skeletal records from the Late Permian of Vyaznilci. Another coprolite fragment contains the etched tooth of a lungfish, while putative actinopterygian fish remains (scales and small fragments of bones) are abundant in some samples. Mineral particles (mostly quartz grains, feldspars and mica) may have been swallowed accidentally. The preserved microbial colonies (mineralized fossil fungi and bacteria or their pseudomorphs), manifested in the coprolites as Fe-rich mineral structures, seem to have developed on the expelled feces rather than on the items before they were swallowed.
|
|
| 3. |
- Nesbitt, Sterling J., et al.
(författare)
-
The earliest bird-line archosaurs and the assembly of the dinosaur body plan
- 2017
-
Ingår i: Nature. - : NATURE PUBLISHING GROUP. - 0028-0836 .- 1476-4687. ; 544:7651, s. 484-
-
Tidskriftsartikel (refereegranskat)abstract
- The relationship between dinosaurs and other reptiles is well established(1-4), but the sequence of acquisition of dinosaurian features has been obscured by the scarcity of fossils with transitional morphologies. The closest extinct relatives of dinosaurs either have highly derived morphologies(5-7) or are known from poorly preserved(8,9) or incomplete material(10,11). Here we describe one of the stratigraphically lowest and phylogenetically earliest members of the avian stem lineage (Avemetatarsalia), Teleocrater rhadinus gen. et sp. nov., from the Middle Triassic epoch. The anatomy of T. rhadinus provides key information that unites several enigmatic taxa from across Pangaea into a previously unrecognized clade, Aphanosauria. This clade is the sister taxon of Ornithodira (pterosaurs and birds) and shortens the ghost lineage inferred at the base of Avemetatarsalia. We demonstrate that several anatomical features long thought to characterize Dinosauria and dinosauriforms evolved much earlier, soon after the bird-crocodylian split, and that the earliest avemetatarsalians retained the crocodylian-like ankle morphology and hindlimb proportions of stem archosaurs and early pseudosuchians. Early avemetatarsalians were substantially more species-rich, widely geographically distributed and morphologically diverse than previously recognized. Moreover, several early dinosauromorphs that were previously used as models to understand dinosaur origins may represent specialized forms rather than the ancestral avemetatarsalian morphology.
|
|
| 4. |
- Niedzwiedzki, Grzegorz, et al.
(författare)
-
Reduction of vertebrate coprolite diversity associated with the end-Permian extinction event in Vyazniki region, European Russia
- 2016
-
Ingår i: Palaeogeography, Palaeoclimatology, Palaeoecology. - : Elsevier BV. - 0031-0182 .- 1872-616X. ; 450, s. 77-90
-
Tidskriftsartikel (refereegranskat)abstract
- This study investigates the paleoecological significance of vertebrate coprolites collected from seven sections and three lithofacies of the uppermost Permian and lowermost Triassic succession from the Vyazniki site in the European part of Russia. The analyzed specimens (coprolites and possibly some cololites) were grouped into nine morphotypes (A-I). The coprolite morphotypes were characterized geochemically and compared to the record of other Permian and Triassic coprolites worldwide. Based on the stratigraphic position, shape, structure and composition, all morphotypes were linked to supposed producers. The phosphatic composition of most of the morphotypes and inclusions of arthropod remains, fish scales and bone fragments, suggest that they were produced by carnivores, but non-phosphatic, carbonate-rich, large and oval-shaped coprolites with impressions after plant remains have also been found. The extinction of terrestrial vertebrates around the Permian-Triassic boundary in Russia is interpreted to have occurred within a few thousands of years. Here, we show a pattern of coprolite morphotypes disappearing across this boundary that is consistent with a relatively sudden change in the vertebrate faunal composition across this interval.
|
|
| 5. |
- Pindakiewicz, Maciej, et al.
(författare)
-
Feeding convergence among ray-finned fishes : Teeth of the herbivorous actinopterygians from the latest Permian of East European Platform, Russia
- 2020
-
Ingår i: Acta Palaeontologica Polonica. - : INST PALEOBIOLOGII PAN. - 0567-7920 .- 1732-2421. ; 65:1, s. 71-79
-
Tidskriftsartikel (refereegranskat)abstract
- A unique functional adaptation to herbivory within early ray-finned fishes is exemplified by the late Permian actinopterygians within the family Etuynotoidiidae with policuspid teeth strongly modified with respect to the primitive actinopterygian conditions. Here we report additional finds of multidenticulated teeth from the fluvial latest Permian deposits of Russia. The teeth belong to the members of endemic Eurynotoidiidae and show rather high morphological diversity. We confirm that the Russian forms are the earliest known ray-finned fishes with substantial modifications of teeth adapted to the processing of food. These finds confirm some previous suggestions that the adaptation to herbivory first developed in freshwater fishes, not marine. We found very similar dental adaptations in some groups of Recent freshwater teleosts, especially in characifonns and cichlids. It suggests that sympatric species of Permian Eurynotoidiidae explored various herbivorous niches like modem fish in East African lakes. Apparently, this first pulse of adaptive radiation in ray-finned fishes was probably caused by diversification of Permian aquatic vertebrate community.
|
|
| 6. |
- Scholze, Frank, et al.
(författare)
-
Early Triassic Conchostracans (Crustacea : Branchiopoda) from the terrestrial Permian-Triassic boundary sections in the Moscow syncline
- 2015
-
Ingår i: Palaeogeography, Palaeoclimatology, Palaeoecology. - : Elsevier BV. - 0031-0182 .- 1872-616X. ; 429, s. 22-40
-
Tidskriftsartikel (refereegranskat)abstract
- The Permian-Triassic boundary marks the greatest mass extinction in Earth's history. In order to understand the real causes of this severe extinction event, multidisciplinary investigations around the globe are required. Here, the terrestrial Permian-Triassic boundary sections in the Vladimir region, Central Russia, were sampled bed-by-bed for conchostracan study. In the Early Triassic intervals the following taxa were recognized for the first time: Cornia germari (Beyrich, 1857), Euestheria gutta (Lutkevitch, 1937), Magniestheria mangaliensis (Jones, 1862), Palaeolimnadiopsis vilujensis Varentsov, 1955, and Rossolimnadiopsis Novozhilov, 1958. The wide distribution of C germari demonstrates their high value for biostratigraphy, since this species was also reported from the Lower Buntsandstein Subgroup in the Germanic Basin as well as from Early Triassic deposits in Hungary, Greenland and Siberia. The assumption of an Early Triassic age of the studied sections is also supported by associated Tupilakosaurus bone fragments, which point to the Tupilakosaurus wedugensis Zone in the earliest Triassic.
|
|
| 7. |
- Scholze, Frank, et al.
(författare)
-
Late Permian conchostracans (Crustacea, Branchiopoda) from continental deposits in the Moscow Syneclise, Russia
- 2019
-
Ingår i: Journal of Paleontology. - : Cambridge University Press (CUP). - 0022-3360 .- 1937-2337. ; 93:1, s. 72-97
-
Tidskriftsartikel (refereegranskat)abstract
- The Moscow Syneclise on the East European Platform is an important area for the study of the continental biota of late Permian to Early Triassic age in continuous sections. This study attempts a taxonomic description of the late Permian conchostracan fauna of this area. The rich, new material was collected, bed by bed, during geological and paleontological excavations of lacustrine and fluvial deposits of the Obnora Formation and Vokhma Formation of the late Permian Zhukovian Regional Stage near the towns of Vyazniki and Gorokhovets. The conchostracan fauna of the Zhukovian Regional Stage consists predominantly of Pseudestheria and less frequently of Palaeolimnadiopsis. In the earliest Triassic Vokhmian Regional Stage, a more diverse fauna including Euestheria, Magniestheria, Cornia, Palaeolimnadiopsis, and Rossolimnadiopsis was already recorded. The preliminary taxonomic determination of the pseudestheriids from the Zhukovian Regional Stage is intended to serve as a prerequisite for future studies of late Permian conchostracan biostratigraphy on the regional to interregional scale.
|
|
