Preferencje help
Polish version English version Język
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 7

Liczba wyników na stronie
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników

Wyniki wyszukiwania

help Sortuj według:

help Ogranicz wyniki do:
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
1
Artykuł dostępny w postaci pełnego tekstu - kliknij by otworzyć plik
Content available

A relict stem salamander: evidence from the Early Cretaceous of Siberia

100%
Skutschas P. P.
Acta Palaeontologica Polonica
|
2016
|
tom 61
|
nr 1
The early evolution of salamanders, which are one of the three living groups of lissamphibians, is not well known. Both stem- and crown-group salamanders first appeared in the Middle Jurassic (Bathonian), but subsequently had different evolutionary histories: stem salamanders were thought to have gone extinct in the Late Jurassic, while crown salamanders persist to the present day. Here, I report the discovery of an indeterminate stem salamander in the Lower Cretaceous (Aptian–Albian) Ilek Formation of Western Siberia. This is new evidence that the most basal salamanders survived beyond the Jurassic–Cretaceous boundary and co-existed with crown-group salamanders during approximately the first 40 million years of the known history of salamanders. The recognition of stem salamanders in the Early Cretaceous of Western Siberia adds to the inventory of taxa that suggest this area was a refugium for various groups of vertebrates with Jurassic affinities.
2
Artykuł dostępny w postaci pełnego tekstu - kliknij by otworzyć plik
Content available

New specimens of albanerpetontid amphibians from the Upper Cretaceous of Uzbekistan

100%
Skutschas P. P.
Acta Palaeontologica Polonica
|
2007
|
tom 52
|
nr 4
The albanerpetontid fossil record in Asia was limited to five dentaries of unidentified genus from the Upper Cretaceous Khodzhakul (lower Cenomanian) and Bissekty (Turonian) formations, Kyzylkum Desert, Uzbekistan. Here I describe two fragmentary frontals from the Khodzhakul local fauna as the first unequivocal record of the genusAlbanerpeton in Asia.
3
Artykuł dostępny w postaci pełnego tekstu - kliknij by otworzyć plik
Content available

A new salamander from the late Paleocene-early Eocene of Ukraine

63%
Skutschas P. P., Gubin Y. M.
Acta Palaeontologica Polonica
|
2012
|
tom 57
|
nr 1
A new neotenic salamander, Seminobatrachus boltyschkensis gen. et sp. nov., is described based on 14 skeletons of late Paleocene–early Eocene age preserved on drill core slabs from the Cherkassy Region, central Ukraine. The new taxon is diagnosed by the following unique combination of characters: dorsal process of premaxilla posteriorly elongate and overlaps frontal; maxilla greatly reduced in size; parietal–squamosal contact absent; vomerine tooth row long and parallel to maxillary arcade; pterygoid has long anterior process; quadrate ossified; marginal and palatal teeth pedicellate; trunk vertebrae amphicoelous, each having a subcentral keel, anterior basapophysis, and spinal nerve foramina; ribs bicipital; carpals and tarsals unossified; and phalangeal formulae of 2−2−3−2 and 2−2−3−4−2 for manus and pes, respectively. Phylogenetic analysis nests S. boltyschkensis within Urodela (i.e., crown−clade salamanders), but its exact phylogenetic position is equivocal, resolving in one of three ways: (1) in an unresolved trichotomy with Salamandra and (Ambystomatidae + (Dicamptodon + Rhyacotriton)) (results obtained in NONA v. 2.0, with the WINCLADA v. 1.00.08 interface; the parsimony ratchet (island hopper) algorithm), (2) as a sister taxon of (Salamandra + (Ambystomatidae + (Dicamptodon + Rhyacotriton))) clade (results obtained in TNT v. 1.1; the implicit enumeration search algorithm) or (3) as a sister taxon of Ambystomatidae (results obtained in PAUP v. 4.0b10; the branch−and−bound search algorithm).
4
Artykuł dostępny w postaci pełnego tekstu - kliknij by otworzyć plik
Content available

A new genus of eutherian mammal from the Early Cretaceous of Transbaikalia, Russia

63%
Averianov A. O., Skutschas P. P.
Acta Palaeontologica Polonica
|
2001
|
tom 46
|
nr 3
5
Artykuł dostępny w postaci pełnego tekstu - kliknij by otworzyć plik
Content available

A new relict stem salamander from the Early Cretaceous of Yakutia, Siberian Russia

39%
Skutschas P. P., Kolchanov V. V., Averianov A. O., Martin T., Schellhorn R., Kolosov P. N., Vitenko D. D.
Acta Palaeontologica Polonica
|
2018
|
tom 63
|
nr 3
A new stem salamander, Kulgeriherpeton ultimum gen. et sp. nov., is described based on a nearly complete atlas from the Lower Cretaceous (Berriasian–Barremian) Teete vertebrate locality in southwestern Yakutia (Eastern Siberia, Russia). The new taxon is diagnosed by the following unique combination of atlantal characters: the presence of a transversal ridge and a depression on the ventral surface of the posterior portion of the centrum; ossified portions of the intercotylar tubercle represented by dorsal and ventral lips; the absence of a deep depression on the ventral surface of the anterior portion of the centrum; the absence of pronounced ventrolateral ridges; the absence of spinal nerve foramina; the presence of a pitted texture on the ventral and lateral surfaces of the centrum and lateral surfaces neural arch pedicels; the presence of a short neural arch with its anterior border situated far behind the level of the anterior cotyles; moderately dorsoventrally compressed anterior cotyles; and the absence of a deep incisure on the distal-most end of the neural spine. The internal microanatomical organization of the atlas is characterized by the presence of a thick, moderately vascularized cortex and inner cancellous endochondral bone. The recognition of stem salamanders and other vertebrates with Jurassic affinities in the Early Cretaceous high-latitude (paleolatitude estimate N 63–70°) vertebrate assemblage of Teete suggests that: (i) the large territory of present day Siberia was a refugium for Jurassic relicts; (ii) there were no striking differences in the composition of high-latitude Yakutian and mid-latitude Western Siberian Early Cretaceous vertebrate assemblages; and (iii) there was a smooth transition from the Jurassic to Cretaceous biotas in North Asia.
6
Artykuł dostępny w postaci pełnego tekstu - kliknij by otworzyć plik
Content available

Femoral histology and growth patterns of the ceratopsian dinosaur Psittacosaurus sibiricus from the Early Cretaceous of Western Siberia

33%
Skutschas P. P., Morozov S. S., Averianov A. O., Leshchinskiy S. V., Ivantsov S. V., Fayngerts A. V., Feofanova O. A., Vladimirova O. N., Slobodin D. A.
Acta Palaeontologica Polonica
|
2021
|
tom 66
|
nr 2
7
Artykuł dostępny w postaci pełnego tekstu - kliknij by otworzyć plik
Content available

Discovery of Middle Jurassic mammals from Siberia

33%
Averianov A. O., Lopatin A. V., Skutschas P. P., Martynovich N. V., Leshchinskiy S. V., RezvyiA.S., Krasnolutskii S. A., Fayngertz A. V.
Acta Palaeontologica Polonica
|
2005
|
tom 50
|
nr 4
789-797
Mammal remains from the Middle Jurassic (Bathonian) Berezovsk Quarry on the south of Krasnoyarsk Territory, West Siberia, Russia are referred to Docodonta indet. (two edentulous fragmentary dentaries) and Mammalia indet. (a single−rooted tooth). The dentaries exemplify a unique combination of plesiomorphic characters found among stem mammals only in Docodonta and Morganucodon: well developed Meckel’s groove, trough for postdentary bones with overhanging medial ridge and a diagonal ridge on the floor separating the “adductor fossa” and angular facet, and well developed and posteroventrally directed pseudangular process with facet for the reflected lamina of angular. Both specimens share with Docodonta the prearticular facet placed ventral to the angular facet and extending posteriorly to the mandibular foramen. This facet is not present in Morganucodon, where the prearticular lies medial to the angular. Medial position of the prearticular in Morganucodon is connected with the compound jaw articulation in this genus, in which a rudimentary articular−quadrate mandibular joint is present medially to the dentary−squamosal joint. In Docodonta indet. from Berezovsk Quarry, Haldanodon and Docodon the position of the prearticular ventral to the angular is connected with the position of the articular complex ventral to the dentary condyle. Such articular complex could not function as a mandibular joint and postdentary bones in Docodonta were used solely for sound transmission. One specimen from Berezovsk Quarry shares with Morganucodon a groove for replacement dental lamina, which was not reported previously for Docodonta. Mammal remains from Berezovsk Quarry are among the oldest occurrences for Docodonta, the first record of Jurassic mammals for Siberia, and only second such record for the whole of Russia.
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.