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Wyświetlanie 1-7 z 7
Tytuł:
Ichnotaxonomy and trackmaker assignment of tetrapod tracks and swimming traces from the Middle Permian Hornburg Formation of Saxony-Anhalt (Germany)
Autorzy:
Buchwitz, Michael
Marchetti, Lorenzo
Jansen, Maren
Falk, Daniel
Trostheide, Frank
Schneider, Joerg W.
Tematy:
rotliegend
tetrapod ichnology
Capitosauroides
Amphisauropus
Therapsida
Konberg
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Wydawca:
Polskie Towarzystwo Geologiczne
Powiązania:
https://bibliotekanauki.pl/articles/1836268.pdf  Link otwiera się w nowym oknie
Opis:
Here we describe new material of tetrapod tracks and swimming traces from the Konberg quarry, a tracksite of the late middle Permian Hornburg Formation in Saxony-Anhalt, central Germany. A relatively well-preserved trackway and several isolated imprints are assigned to Capitosauroides isp. Among others, toe proportions in the manus and pes footprints of the newly described specimens and the long, proximal and detached pedal digit V imprint are similar to the type ichnospecies Capitosauroides bernburgensis from the Early Triassic of Bernburg, Saxony-Anhalt. In these features the new Konberg material differs from other ichnotaxa, such as Amphisauropus and Varanopus, which may look similar in their relative length of the sole, digit proportions and/or in the digit tip imprint morphology. The comparatively large manus imprint, which is wider than long, the relative length and shape of the sole impression, the digit proportions that are indicative for a more ectaxonic manus a more mesaxonic pes, the low pace angulation and the low imprint-size-normalized stride length in the Konberg track type are distinct from C. bernburgensis. It shares, however, a certain similarity with recently described material of Capitosauroides from middle-late Permian tracksites. These observations are in agreement with the results of a multivariate analysis including Capitosauroides and morphologically similar ichnotaxa. Our findings would justify the erection of a new ichnospecies if more trackways with a similar or slightly better preservation were at hand. Hornburg Formation material previously assigned to Amphisauropus is herein considered as indetermined tetrapod tracks, whereas the oc-currence of Dromopus isp. is confirmed. This reassignment shortens the stratigraphic range of the ichnogenus Amphisauropus,which appears to be restricted to the early Permian, since younger occurrences are questionable. In agreement with the attribution of Capitosauroides to eutheriodont producers, we regard the Konberg material assigned to this ichnogenus as tracks of small and possibly semi-aquatic therapsids. Abundant tetrapod swimming traces that co-occur with Capitosauroides isp. on the same bedding planes are interpreted as having been made by the same group of producers. The subaquatic traces often consist of short parallel claw mark sets. In agreement with a derived amniote producer group, they indicate propulsion by parasagittal limb movement rather than axial undulation.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Palaeoneurology and palaeobiology of the dinocephalian therapsid Anteosaurus magnificus
Autorzy:
Benoit, J.
Kruger, A.
Jirah, S.
Fernandez, V.
Rubidge, B.S.
Tematy:
Therapsida
Dinocephalia
head-butting
carnivory
trigeminal nerve
bony labyrinth
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Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Powiązania:
https://bibliotekanauki.pl/articles/2082279.pdf  Link otwiera się w nowym oknie
Opis:
Dinocephalians (Therapsida), some of the earliest amniotes to have evolved large body size, include the carnivorous Anteosauria and mostly herbivorous Tapinocephalia. Whilst the palaeoneurology of the Tapinocephalia has been investigated in Moschognathus whaitsi, that of the Anteosauria remains completely unknown. Here we used X-ray micro-Computed Tomography to study, for the first time, the palaeoneurology of Anteosaurus magnificus. Compared to Moschognathus, we reconstruct Anteosaurus as an agile terrestrial predator based on the enlarged fossa for the floccular lobe of the cerebellum and semicircular canals of the inner ear. A major difference between the two genera resides in the orientation of the braincase, as indicated by the angle between the long axis of the skull and the plane of the lateral semicircular canal. This angle is 25° in Anteosaurus, whereas it is 65° in Moschognathus, which suggests that the braincase of the latter was remodelled as an adaptation to head-butting. This is consistent with less cranial pachyostosis and the retention of a large canine in Anteosauria, which suggests that dentition may have been used for intraspecific fighting and display in addition to trophic interactions. The evolution of a thick skull, horns, and bosses in tapinocephalids parallels the evolutionary reduction of the canine, which lead to a shift of the agonistic function from the mouth to the skull roof, as observed in extant social ungulates. Similarly, tapinocephalians may have developed complex social behaviour.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The sixth sense in mammalian forerunners: variability of the parietal foramen and the evolution of the pineal eye in South African Permo-Triassic eutheriodont therapsids
Autorzy:
BENOIT, JULIEN
ABDALA, FERNANDO
MANGER, PAUL R.
RUBIDGE, BRUCE S.
Tematy:
therapsida
pineal
parietal foramen
third eye
endothermy
permian
triassic
south africa
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Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Powiązania:
https://bibliotekanauki.pl/articles/945457.pdf  Link otwiera się w nowym oknie
Opis:
In some extant ectotherms, the third eye (or pineal eye) is a photosensitive organ located in the parietal foramen on the midline of the skull roof. The pineal eye sends information regarding exposure to sunlight to the pineal complex, a region of the brain devoted to the regulation of body temperature, reproductive synchrony, and biological rhythms. The parietal foramen is absent in mammals but present in most of the closest extinct relatives of mammals, the Therapsida. A broad ranging survey of the occurrence and size of the parietal foramen in different South African therapsid taxa demonstrates that through time the parietal foramen tends, in a convergent manner, to become smaller and is absent more frequently in eutherocephalians (Akidnognathiidae, Whaitsiidae, and Baurioidea) and non-mammaliaform eucynodonts. Among the latter, the Probainognathia, the lineage leading to mammaliaforms, are the only one to achieve the complete loss of the parietal foramen. These results suggest a gradual and convergent loss of the photoreceptive function of the pineal organ and degeneration of the third eye. Given the role of the pineal organ to achieve fine-tuned thermoregulation in ectotherms (i.e., “cold-blooded” vertebrates), the gradual loss of the parietal foramen through time in the Karoo stratigraphic succession may be correlated with the transition from a mesothermic metabolism to a high metabolic rate (endothermy) in mammalian ancestry. The appearance in the eye of melanopsin-containing retinal ganglion cells replacing the photoreceptive role of the pineal eye could also have accompanied its loss.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The origins of the cochlea and impedance matching hearing in synapsids
Autorzy:
Laaß, M.
Tematy:
origin
cochlea
Therapsida
Anomodontia
tympanic hearing
Permian
South Africa
synapsid
tetrapod
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Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Powiązania:
https://bibliotekanauki.pl/articles/20432.pdf  Link otwiera się w nowym oknie
Opis:
The origin of tympanic hearing in early synapsids is still controversial, because little is known about their inner ear and the function of their sound conducting apparatus. Here I describe the earliest known tympanic ear in the synapsid lineage, the ear of Pristerodon (Therapsida, Anomodontia) from the Late Permian of South Africa, which was virtually reconstructed from neutron tomographic data. Although Pristerodon is not a direct ancestor of mammals, its inner ear with distinctive cochlear cavity represents a connecting link between the primitive therapsid inner ear and the mammalian inner ear. The anatomy of the sound conducting apparatus of Pristerodon and the increased sound pressure transformer ratio points to a sensitivity to airborne sound. Furthermore, the origins of the cochlea and impedance matching hearing in synapsids coincided with the loss of contact between head and substrate, which already took place at least in Late Permian therapsids even before the postdentary bones became detached from the mandible.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
New features of the snout and orbit of a therocephalian therapsid from South Africa
Autorzy:
Sigurdsen, T
Tematy:
Akidnognathidae
dentition
Karoo basin
Therocephalia
therocephalian therapsid
South Africa
tooth
Therapsida
Synapsida
paleontology
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Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Powiązania:
https://bibliotekanauki.pl/articles/21325.pdf  Link otwiera się w nowym oknie
Opis:
I describe the anterior part of the externally poorly preserved skull of a therocephalian from the Karoo Basin in South Africa, using the method of serial grinding. The skull is incomplete, and its estimated length in life is 130 mm. The skull can be assigned to the Akidnognathidae with some confidence. The stratigraphic age of the specimen and its locality are not known, but the surrounding sediment suggests that it may be from the Upper Permian Dicynodon Assemblage Zone. It has five or six postcanine teeth, and a poorly developed crista choanalis. The sinuses and canals of the snout are recognized, and it is believed that the sinus positioned posteriorly in the snout (posterior maxillary sinus) is homologous with the maxillary sinus of anomodonts and cynodonts. It also shows similarities to the infraorbital canal of early mammals, such as Morganucodon. An anteriorly positioned sinus (anterior maxillary sinus), situated directly behind the canine root, is homologized with the maxillary sinus of gorgonopsians. In addition, I identify the previously undescribed canal (designated anterior maxillary canal), leading from the anterior maxillary sinus antero−dorsally. No evidence for maxilloturbinals was found in contrast to the condition known in the primitive therocephalian Glanosuchus
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
New basal synapsid supports Laurasian origin for therapsids
Autorzy:
Liu, J
Rubidge, B.
Li, J.
Tematy:
synapsid
Laurasia
therapsid
fossil
paleontology
China
Therapsida
Dashankou
Permian
fauna
Gansu province
tetrapod fossil
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Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Powiązania:
https://bibliotekanauki.pl/articles/21774.pdf  Link otwiera się w nowym oknie
Opis:
The distant evolutionary ancestry of mammals is documented by a rich therapsid fossil record. While sphenacodontid synapsids are considered the sister−group of therapsids, the place of origin of therapsids is an enigma, largely because of a long standing morphological and temporal gap (Olson’s Gap) in their fossil record. We describe a new large predatory synapsid, Raranimus dashankouensis gen. et sp. nov., from the Middle Permian of Dashankou in China which has a unique combination of therapsid and sphenacodontid features. This specimen is of great significance asit is a basal therapsid which is the sister taxon to all other therapsids. The fact that it was found in association with Early Permian tetrapods (Anakamacops and Belebey) suggests that it is the oldest therapsid and provides the first evidence of therapsid−bearing rocks which cover Olson’s Gap. It further supports that therapsids may have had a Laurasian rather than Gondwanan origin.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the affinities of Tetraceratops insignis, an Early Permian synapsid
Autorzy:
Amson, E.
Laurin, M.
Tematy:
Tetraceratops insignis
Early Permian
Permian
synapsid
Therapsida
phylogenesis
biogeography
range extension
Paleozoic
Pangaea
North America
fossil
paleontology
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Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Powiązania:
https://bibliotekanauki.pl/articles/20520.pdf  Link otwiera się w nowym oknie
Opis:
The affinities of the Early Permian synapsid Tetraceratops insignis have been reevaluated several times since the early 20th century, being considered as an eothyridid, a sphenacodontid, or a therapsid. This controversy continues into the 21st century, with recently raised doubts about the interpretation of Tetraceratops as the oldest known therapsid, a hypothesis supported by the only redescription of this fossil in the second half of the 20th century. Our study examines the arguments proposed to refute therapsid affinities, and concludes that Tetraceratops indeed is the sister−group of all other known therapsids. The most recently published phylogenetic data matrix that includes Tetraceratops fails to confirm its therapsid affinities. However, adding seven characters to that matrix leads to the conclusion that Tetraceratops is the basal−most and oldest therapsid. The recent suggestion of a Laurasian origin of therapsids appears poorly supported; too few data are available on the distribution of Permian synapsids to settle this question.
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-7 z 7

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