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Tytuł:
A new genus of eutherian mammal from the Early Cretaceous of Transbaikalia, Russia
Autorzy:
Averianov, A O
Skutschas, P.P.
Powiązania:
https://bibliotekanauki.pl/articles/21830.pdf
Data publikacji:
2001
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
eutherian mammal
fossil record
Early Cretaceous
history
Transbaikalia
mammal
Cretaceous
Russia
new genus
Prokennalestes abramovi
Źródło:
Acta Palaeontologica Polonica; 2001, 46, 3
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Early Cretaceous symmetrodont mammal Gobiotheriodon from Mongolia and the classification of Symmetrodonta
Autorzy:
Averianov, A O
Powiązania:
https://bibliotekanauki.pl/articles/20946.pdf
Data publikacji:
2002
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Gobiotheriodon infinitus
systematics
classification
Early Cretaceous
mammal
Cretaceous
Mongolia
Gobiotheriodon
paleontology
Opis:
The “symmetrodont” mammal, Gobiotheriodon infinitus (Trofimov, 1980), from the Early Cretaceous (Aptian–Albian) of Mongolia, is redescribed.The species is restricted to the holotype only (dentary with three last molars), the referred maxillary fragment with M3? is considered here as cf. Gobiconodon sp.The dental formula of G. infinitusis reinterpreted as i1–3 c1 p1–3 m1–4. G. infinitus is characterized by a short dentary symphysis; long, well−developed Meckel's groove; small, triangular−shaped pterygoid fossa; weakly developed pterygoid crest; i3 enlarged; p1–3 two−rooted; lower molars acute− to obtuse−angled, labial cingulids lacking, lingual cingulids very short, well developed mesial and distal cingulid cuspules (“e” and “d”) and prominent wear surface on the paracristid. Gobiotheriodon is similar to Tinodon (Late Jurassic, USA; Early Cretaceous, Great Britain and Portugal) in postcanine dental formula and structure of the pterygoid fossa; it is provisionally assigned to Tinodontidae Marsh, 1887.Some taxa previously assigned to (or suggested as possible relatives of) “Symmetrodonta” are reviewed.Amphidontidae Simpson, 1925 is considered as nomen dubium.A new classification for “Symmetrodonta” is proposed.
Źródło:
Acta Palaeontologica Polonica; 2002, 47, 4
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A reassessment of Kelmayisaurus petrolicus, a large theropod dinosaur from the Early Cretaceous of China
Autorzy:
Brusatte, S.L.
Benson, R.B.J.
Xu, X.
Powiązania:
https://bibliotekanauki.pl/articles/21593.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
paleontology
Kelmayisaurus petrolicus
large theropod dinosaur
theropod dinosaur
Early Cretaceous
China
Dinosauria
Theropoda
Carcharodontosauridae
anatomy
Cretaceous
Opis:
The Early Cretaceous fossil record of large−bodied theropods from Asia is poor, hindering comparison of Asian predatory dinosaur faunas with those from other continents. One of the few large Asian theropod specimens from this interval is a partial skull (maxilla and dentary) from the Lianmugin Formation (?Valanginian–Albian), the holotype of Kelmayisaurus petrolicus. Most authors have either considered this specimen as an indeterminate basal tetanuran or a nomen dubium. We redescribe K. petrolicus and note that it possesses a single autapomorphy (a deep accessory groove on the lateral surface of the anterior dentary), as well as a unique combination of characters that differentiates it from other theropods, affirming its validity. A phylogenetic analysis recovers K. petrolicus as a basal carcharodontosaurid, which is supported by various features: very deep interdental plates (a carcharodontosaurid synapomorphy), fused interdental plates (present in carchardontosaurids and a limited number of other theropods), and the absence of diagnostic features of other clades of large−bodied theropods such as abelisaurids, megalosauroids, and coelurosaurs. As such,Kelmayisaurusis the second known carcharodontosaurid from Asia, and further evidence that this clade represented a global radiation of large−bodied predators during the Early–mid Cretaceous.
Źródło:
Acta Palaeontologica Polonica; 2012, 57, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bone microstructure and growth patterns of early mammals
Autorzy:
Chinsamy, A
Hurum, J.H.
Powiązania:
https://bibliotekanauki.pl/articles/23349.pdf
Data publikacji:
2006
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
fossil record
Eutheria
mammal
Cretaceous
Mammalia
growth rate
Early Jurassic
Morganucodonta
Multituberculata
paleontology
bone microstructure
Cynodontia
Opis:
We present results of the first studies of the bone microstructure of early mammals, based on the Early Jurassic Morganucodon, the Late Cretaceous multituberculates, Kryptobaatar and Nemegtbaatar, and the Late Cretaceous eutherians Zalambdalestes and Barunlestes. Our results show that the two eutherian taxa grew relatively slowly with periodic pauses in growth indicated by the presence of rest lines, while the multituberculates and Morganucodon had a faster rate of bone formation that suggests an overall rapid growth rate that slowed down later in ontogeny. Comparisons of the early mammalian bone microstructure with that of non−mammalian cynodonts, extant monotremes, and placentals are also made, and significant differences in the rate of osteogenesis in the various groups are documented. Our findings suggest differences in the growth rate between the multituberculates and the Mesozoic eutherians, and moreover, both groups appear to have slower growth rates as compared to modern monotremes and placentals. Our results further suggest that the determinate growth strategy typical of extant mammals evolved early in the evolution of the non−mammalian therapsids. We speculate that the sustained, uninterrupted bone formation among the multituberculates may have been an adaptive attribute prior to the K−T event, but that the flexible growth strategy of the early eutherians was more advantageous thereafter.
Źródło:
Acta Palaeontologica Polonica; 2006, 51, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A new gobiconodontid mammal from the Early Cretaceous of Spain and its palaeogeographic implications
Autorzy:
Cuenca-Bescos, G
Canudo, J.I.
Powiązania:
https://bibliotekanauki.pl/articles/20043.pdf
Data publikacji:
2003
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
new gobiconodontid
Early Cretaceous
gobiconodontid mammal
mammal
Cretaceous
Spain
gobiconodontid
fossil
Gobiconodontidae
Mammalia
Barremian
Europe
paleogeography
Opis:
A new gobiconodontid from Vallipón (Teruel, Spain) represents the first record of this family in Europe. The site has a diverse fossil assemblage mainly composed of isolated bones and teeth probably accumulated by tidal action and water streams in an ancient beach of upper Barremian, in the transitional marine−continental sediments of the Artoles Formation. The new gobiconodontid consist of an isolated upper molar, smaller in size than that element in other gobiconodontids, with a robust cusp A, characterised by lateral bulges on each mesial and distal flanges of that cusp, and a discontinuous cingulum raised at the lingual side. The occlusal outline is smooth compared with Gobiconodon borissiaki, Gobiconodon hoburensis, or Gobiconodon ostromi. The Gobiconodontidae record is exclusively Laurasiatic. The oldest gobiconodontid fossil remains are Hauterivian; though their probable origin has to be found at the Late Jurassic in Central Asia (as inferred from derived character of the first gobiconodontids as well as phylogenetic relationships). At the end of the Early Cretaceous they expanded throughout Laurasia as indicated by findings in Asia, North America, and Spain. Two dispersion events spread gobiconodontids: to the West (Europe) in the Barremian and to the East (North America) during the Aptian/Albian.
Źródło:
Acta Palaeontologica Polonica; 2003, 48, 4
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A basal eucryptodiran turtle 'Sinemys' efremovi [-Waguia efremovi] from the Early Cretaceous of China
Autorzy:
Danilov, I G
Sukhanov, V.B.
Powiązania:
https://bibliotekanauki.pl/articles/21804.pdf
Data publikacji:
2006
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Early Cretaceous
Cretaceous
Testudines
turtle
China
eucryptodiran turtle
Junggar Basin
Macrobaenidae
Eucryptodira
Wuguia efremovi
Sinemys efremovi
paleontology
Opis:
A reexamination of the type material (two specimens considered for a long time lost) of the poorly known turtle “Sinemys” efremovi Khosatzky, 1996 from the Early Cretaceous Tugulu Group of northwest China, allows us to present new observations, images, and taxonomic conclusions about these important specimens. We conclude that: (1) “S.” efremovi is referrable to the basal eucryptodire genus Wuguia Matzke, Maisch, Pfretzschner, Sun, and Stöhr, 2004 based on a small size (up to 150 mm in shell length), absence of the nuchal emargination, presence of additional ossifications in the suprapygal region of the carapace and similar plastral proportions with relatively long bridges (35−45% of the plastron width), and a narrow and elongated posterior lobe; (2) “S.” efremovi is a senior subjective synonym of Dracochelys wimani Maisch, Matzke, and Sun, 2003, another species recently described from the Tugulu Group. As construed here, Wuguia includes two species: W. efremovi (Khosatzky, 1996) and W. hutubeiensis Matzke, Maisch, Pfretzschner, Sun, and Stöhr, 2004. New diagnoses for these taxa are given.
Źródło:
Acta Palaeontologica Polonica; 2006, 51, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Reappraisal of the tribosphenidan mammals from the Trinity Group (Aptian-Albian) of Texas and Oklahoma
Autorzy:
Davis, B.M.
Cifelli, R.L.
Powiązania:
https://bibliotekanauki.pl/articles/21832.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
tribosphenidan mammal
mammal
Tribosphenida
Metatheria
Eutheria
Deltatheroida
Trinity Group
Texas
Oklahoma
paleontology
taxonomy
Oklatheridium
Pappotherium
Holoclemensia
Kermackia
Slaughteria
Early Cretaceous
Cretaceous
Opis:
The Trinity therians have long been the focus of attempts to reconstruct the evolutionary history of higher mammals, especially in the context of the development of tribospheny. In this paper, we update the taxonomy of the tribosphenidan taxa known from the Trinity Group and establish with more confidence the premolar/molar count in each. Many isolated specimens can be referred to a specific tooth locus. Additional diversity is revealed within the Deltatheroida, with the description of an additional species of Oklatheridium; Pappotherium is here considered a likely metatherian based on the inferred presence of four molars, while Holoclemensia is a basal eutherian (the opposite of some traditional interpretations). The remainder of the genera, Kermackia and Slaughteria, cannot be allied with either of the living groups of tribosphenidan mammals using the available data. We identify strong morphological diversity within this assemblage of stem taxa, including modifications to the traditional tribosphenic occlusal pattern in Kermackia. Mammalian evolution at the base of the tribosphenidan radiation was complex, and this underscores the need for caution when interpreting the morphology and relationships of taxa known by incomplete material.
Źródło:
Acta Palaeontologica Polonica; 2011, 56, 3
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A nearly complete ornithocheirid pterosaur from the Aptian (Early Cretaceous) Crato Formation of NE Brazil
Autorzy:
Elgin, R.A.
Frey, E.
Powiązania:
https://bibliotekanauki.pl/articles/19983.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
ornithocheirid pterosaur
pterosaur
Aptian
Early Cretaceous
Cretaceous
Crato Formation
Brazil
Ornithocheiroidea
Opis:
A partial ornithocheirid, representing a rare example of a pterosaurian body fossil from the Nova Olinda Member of the Crato Formation, NE Brazil, is described from the collections of the State Museum of Natural History, Karlsruhe. While similar in preservation and taphonomy to Arthurdactylus conandoylei, it is distinguished by slight differences in biometric ratios, but the absence of a skull prevents closer identification. Mostly complete body fossils belonging to ornithocheiroid pterosaurs appear to be relatively more abundant in the younger Romualdo Member of the Santana Formation, making the described specimen one of only two well documented ornithocheiroids known from the Nova Olinda Lagerstätte.
Źródło:
Acta Palaeontologica Polonica; 2012, 57, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Demandasaurus darwini, a new rebbachisaurid sauropod from the Early Cretaceous of the Iberian Peninsula
Autorzy:
Fernandez-Baldor, F.T.
Canudo, J.I.
Huerta, P.
Montero, D.
Pereda Suberbiola, X.
Salgado, L.
Powiązania:
https://bibliotekanauki.pl/articles/22403.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Demandasaurus darwini
new species
rebbachisaurid sauropod
sauropod
paleontology
Early Cretaceous
Cretaceous
Iberian Peninsula
Spain
Sauropoda
Rebbachisauridae
systematics
paleobiogeography
Opis:
A new medium−sized rebbachisaurid sauropod from the Castrillo la Reina Formation (Upper Barremian–Lower Aptian) in Burgos Province, Demandasaurus darwini gen. et sp. nov., is described. It is known from an incomplete but associated skeleton that includes cranial and post−cranial remains. Demandasaurus darwini gen. et sp. nov. presents 9 autapomorphies in the teeth and vertebrae. Demandasaurus is the first diplodocoid sauropod described from the Cretaceous of the Iberian Peninsula. Its inclusion in the Rebbachisauridae is well supported by our phylogenetic hypothesis, which situates it as a sister group of Nigersaurus from the Aptian of Niger, with which it shares various synapomorphies. The discovery of Demandasaurus provides further evidence of the sporadic use of the Apulian Route by dinosaurs during the Early Cretaceous for moving between the south of Europe (Laurasia) and the north of Africa (Gondwana).
Źródło:
Acta Palaeontologica Polonica; 2011, 56, 3
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
New albanerpetontid amphibians from the Early Cretaceous of Morocco and Middle Jurassic of England
Autorzy:
Gardner, J D
Evans, S.E.
Sigogneau-Russell, D.
Powiązania:
https://bibliotekanauki.pl/articles/21595.pdf
Data publikacji:
2003
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Early Cretaceous
Middle Jurassic
Cretaceous
England
Albanerpetontidae
amphibian
albanerpetontid amphibian
Ramonellus
Morocco
Jurassic
paleontology
Lissamphibia
Opis:
A third albanerpetontid genus, Anoualerpeton gen. nov., is erected for two new species: An. unicussp. nov. (type species) from the Early Cretaceous (Berriasian) of Morocco and An. priscus sp. nov. from the Middle Jurassic (late Bathonian) of England. Anoualerpeton differs from the exclusively Laurasian albanerpetontid genera Albanerpeton (Early Cretaceous– Paleocene, North America; Miocene, Europe) and Celtedens (?Late Jurassic and Early Cretaceous, Europe) in a unique combination of primitive and derived character states of the jaws and azygous frontals. Monophyly of Anoualerpeton is supported by two synapomorphies of the maxilla and dentary (occlusal margin convex in labial outline and teeth strongly heterodont in size anteriorly) that are convergent with an unrelated, relatively derived Late Cretaceous species of Albanerpeton from North America. The two species of Anoualerpeton differ in character states of the premaxilla and azygous frontals. Cladistic analysis of 20 characters scored for ten albanerpetontid taxa postulates Anoualerpeton as the sister−taxon of Albanerpeton + Celtedens. The sister−pair of Albanerpeton + Celtedensis founded on one or, perhaps, two premaxillary synapomorphies. Anoualerpeton unicus documents the only known Gondwanan occurrence for the Albanerpetontidae and provides a minimum age of basal Cretaceous for the establishment of the clade in Africa. Characters of the mandible, vertebrae, and limbs support the interpretation that Ramonellus (Aptian; Israel) is a caudate, not an albanerpetontid.
Źródło:
Acta Palaeontologica Polonica; 2003, 48, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Główne elementy paleogeograficzne Zachodnich Karpat zewnętrznych w późnej jurze i wczesnej kredzie
Main paleogeographical elements of the West Outer Carpathians during Late Jurassic and Early Cretaceous times
Autorzy:
Golonka, J.
Krobicki, M.
Waśkowska-Oliwa, A.
Vasicek, Z.
Skupien, P.
Powiązania:
https://bibliotekanauki.pl/articles/184048.pdf
Data publikacji:
2008
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
Karpaty zewnętrzne
paleogeografia
tektonika płyt
jura późna
kreda wczesna
Outer Carpathians
paleogeography
plate tectonics
Late Jurassic
Early Cretaceous
Opis:
Praca koncentruje się na elementach ważnych dla zrozumienia paleogeografii Zachodnich Karpat zewnętrznych w późnej jurze i wczesnej kredzie w nawiązaniu do litostratygrafii różnych stref facjalnych i opracowania skał macierzystych tworzących się w tym okresie. Opisano szereg elementów paleograficznych: Tetyda alpejska i basen magurski, grzbiet ślaski, basen seweryńsko-mołdawidzki oraz platforma północnoeuropejska. W obrębie tej platformy wyróżniono strefy wyniesione: grzbiet Baska-Inwałd oraz pawłowska platforma węglanowa, a także strefy basenowe: basen bachowicki i basen mikułowski.
The present paper concentrates on the elements important to understanding the paleogeography of the West Carpathians during Late Jurassic and Early Cretaceous times. These elements are linked to the lithostratigraphy of the various facies zones as well as occurrence of hydrocarbon source rocks. Several paleogeographic elements have been described: the Alpine Tethys, Magura Basin, Silesian Ridge, Severin-Moldavidic Basin and North European Platform. The uplifted and basinal zones were distinguished within the platform. The Baska-Inwałd Ridge and Pavlov Carbonate Platform belong to the uplifted elements, while Bachowice and Mikulov basins represent the basinal zones.
Źródło:
Geologia / Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie; 2008, 34, 3/1; 61-72
0138-0974
Pojawia się w:
Geologia / Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
New multituberculate teeth from the Early Cretaceous of Morocco
Autorzy:
Hahn, G
Hahn, R.
Powiązania:
https://bibliotekanauki.pl/articles/22382.pdf
Data publikacji:
2003
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
multituberculate
Denisodon
Early Cretaceous
fossil
Paulchoffatioidea
Cretaceous
Mammalia
remains
Morocco
Multituberculata
multituberculate tooth
paleontology
Opis:
Three new multituberculate teeth are described from the Early Cretaceous of Morocco. Denisodon moroccensis gen. et sp. nov. is established for a second lower molar which differs from that of Hahnodon taqueti, from the same locality, by a preserved posterior buccal cusp, a smaller posterior lingual cusp and the less indented lingual wall of the crown. The second tooth is a posterior upper premolar. It is represented by the posterior portion of its crown on which is present only one row of cusps, similar to the conditions in Kielanodon, Eobaatar, Bolodon, and the Pinheirodontidae. The third tooth is a lower incisor, similar to that in Kuehneodon. Both teeth are grouped as „Hahnodontidae, gen. et sp. indet.” Paulchoffatioidea new superfamily is established for the Paulchoffatiidae, Hahnodontidae, and Pinheirodontidae. It is characterized by the following autapomorphies: premolarisation of I2−C, presence of a third row of cusps on the posterior upper premolars and the basin−like structure of the m2. Hahnodontidae and Hahnodon are redefined.
Źródło:
Acta Palaeontologica Polonica; 2003, 48, 3
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Gradual evolution of the Early Cretaceous marine gastropod Rissoina lineage in Central Poland
Autorzy:
Kaim, A
Powiązania:
https://bibliotekanauki.pl/articles/20375.pdf
Data publikacji:
2002
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Buvignieria
gradual evolution
gastropod
Early Cretaceous
Ancient Lake Concept
marine gastropod
Polska
Rissoina
Cretaceous
paleontology
Opis:
The evolutionary changes of the Early Cretaceous (Valanginian) marine gastropod Rissoina (Buvignieria) sp. from Wąwał (central Poland) show a pattern typical of the Ancient Lake Concept. Its morphology is stable during period of unstable conditions and starts to change gradually when the environment becomes stable. The linear character of the evolutionary changes of Rissoina sp. and lack of evolution among co−occuring gastropods suggests that the rate of evolution was controlled by intrinsic factors, not the environment.
Źródło:
Acta Palaeontologica Polonica; 2002, 47, 4
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Humeral torsion in multituberculate mammals
Autorzy:
Kielan-Jaworowska, Z
Powiązania:
https://bibliotekanauki.pl/articles/22733.pdf
Data publikacji:
1998
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Early Cretaceous
mammal skull
Eocene
mammal
Mongolia
humerus
Late Jurassic
small mammal
paleontology
multituberculate mammal
fossil state
Źródło:
Acta Palaeontologica Polonica; 1998, 43, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Primitive boreosphenidan mammal [?Deltatheroida] from the Early Cretaceous of Oklahoma
Autorzy:
Kielan-Jaworowska, Z
Cifelli, R L
Powiązania:
https://bibliotekanauki.pl/articles/21171.pdf
Data publikacji:
2001
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Oklahoma
Early Cretaceous
Boreosphenida
Cretaceous
Atokatheridium boreni
primitive mammal
Deltatheroida
boreosphenidan mammal
Aegialodontidae
Opis:
We describe a new boreosphenidan mammal, Atokatheridium boreni gen. et sp. n., from the Early Cretaceous of Oklahoma, based on an upper molar and a tentatively referred lower molar. The upper molar is characterized by a small protocone and unwinged conules, broad stylar shelf, paracone taller than metacone, and lack of pre- and postcingula. Comparisons with relevant Early and Late Cretaceous boreosphenidans suggest closest similarity to Deltatheroida, including one character (extreme development of the distal stylar shelf, which projects labially and lacks cusps) interpreted as derived. The tentatively attributed lower molar shows similarity to Deltatheridium and the ?aegialodontid genus Kielantherium in having the paraconid higher than the metaconid, but differs from Kielantherium in having a differently shaped talonid. From Aegialodon it differs in having a vertically oriented (rather than semi-procumbent) paraconid and a larger talonid. We figure also two isolated trigonids, differing in size, which show some resemblance to that of ?Atokatheridium. Deltatheroidans, despite their generally primitive dental morphology, are otherwise surely known only from the Late Cretaceous, and are largely restricted to the Old World. If a deltatheroidan, the new taxon implies a significant temporal range extension for the group, and provides another biogeographic link between Cretaceous mammals of Asia and North America.
W pracy opisano nowy gatunek i rodzaj prymitywnego ssaka o zębach trybosfenicznych - Atokatheridium boreni, z wczesnej kredy stanu Oklahoma w Stanach Zjednoczonych. Nowy takson oparty jest na dobrze zachowanym górnym zębie trzonowym i na dolnym trzonowcu, zaliczonym z zastrzeżeniem. Atokatheridium zostal zaliczony do podgromady Boreosphenida, obejmującej ssaki o zębach trybosfenicznych, które powstały na Półkuli Północnej zapewne we wczesnej kredzie. Do Boreosphenida należą wszystkie współcześnie żyjące ssaki właściwe - torbacze i łożyskowce, ich kopalni przedstawiciele, oraz formy wymarłe o zębach trybosfenicznych, których stanowisko systematyczne jest nieustalone. Atokatheridium jest jednym z najstarszych znanych przedstawicieli boreosfenidów. Górny trzonowiec nowego taksonu charakteryzuje się małym protokonem, konulami pozbawionymi skrzydełek, bardzo szeroką półką stylarną, oraz brakiem przednich i tylnych wałeczków (cingulum). Porównanie z zębami wczesno- i późnokredowych boresosfenidów wskazuje, że Atokatheridium najbardziej jest zbliżony do przedstawicieli późnokredowego rzędu Deltatheroida, który należy do Metatheria i stanowi grupę siostrzaną torbaczy. Cechą wspólną jest obecność bardzo rozszerzonej części dystalnej półki stylarnej, kt6ra wystaje w kierunku dowargowym i jest pozbawiona guzków stylarnych. Z drugiej strony, dolny trzonowiec zaliczony z zastrzeżeniem do Atokatheridium wykazuje podobieństwo zarówno do trzonowców deltateroidów, jak i do słabo poznanej grupy wczesnokredowych boreosfenidów - egialodontów, szczególnie do rodzaju Kielantherium. W pracy zilustrowano takze dwa niekompletne dolne trzonowce (trygonidy) pochodzące z tej samej formacji co Atokatheridium, które wykazują pewne podobieństwo do trzonowca zaliczonego z zastrzeżeniem do Atokatheridium. Rząd Deltatheroida, który charakteryzuje się ogólnie prymitywną budową zębów i ma wzór zębowy taki jak torbacze, znany był dotąd tylko z późnej kredy i tylko z Pólkuli Północnej. Jeżeli Atokatheridium należy rzeczywiście do Deltatheroida, to wskazywałoby to że deltateroidy pojawiły się we wczesnej kredzie.
Źródło:
Acta Palaeontologica Polonica; 2001, 46, 3
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 46

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