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    Wyświetlanie 1-11 z 11
    Tytuł:
    A eutherian mammal in the latest Cretaceous of Vitrolles, Southern France
    Autorzy:
    Tabuce, R
    Vianey-Liaud, M.
    Garcia, G.
    Powiązania:
    https://bibliotekanauki.pl/articles/22800.pdf
    Data publikacji:
    2004
    Wydawca:
    Polska Akademia Nauk. Instytut Paleobiologii PAN
    Tematy:
    eutherian mammal
    Eutheria
    mammal
    Cretaceous
    Mammalia
    Vitrolles
    France
    paleontology
    Opis:
    In Europe, the fossil record of the eutherian mammals is very scanty for the Late Cretaceous, as only two genera, documented by isolated teeth, are presently recorded in France and in Spain. Both genera, Labes and Lainodon, are considered to be representatives of the “zhelestids”, a paraphyletic unit regarded as being at the origin of Cenozoic ungulates within the Ungulatomorpha clade. We here describe Valentinella vitrollense gen. et sp. nov. from Vitrolles la Plaine (Maastrichtian, southern France). This species, represented by fragmentary remains of lower and upper dentitions, is tentatively assigned to the “zhelestids” according to the hypoconulid−entoconid twinning and the antero−posteriorly short trigonid on m1–3. The occlusal surfaces are obliterated by dental attrition, but Valentinella could be an evolved “zhelestid”, more derived than Labes and Lainodon by its fully compressed trigonid. Valentinella is similar to Gallolestes by other derived characters such as a crushing specialization of the teeth, associated with a probably molariform p4 (or dp4) and slightly reduced m3. The enamel microstructure, showing a radial prismatic pattern combined with a reduced interprismatic matrix, in which cristallites are oriented at about 45° to the prisms axes, appears compatible with the ancestral morphotype for all ungulates; although no synapomorphy can be proposed for the ungulatomorphs.
    Źródło:
    Acta Palaeontologica Polonica; 2004, 49, 3
    0567-7920
    Pojawia się w:
    Acta Palaeontologica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Highly derived eutherian mammals from the earliest Cretaceous of southern Britain
    Autorzy:
    SWEETMAN, STEVEN C.
    SMITH, GRANT
    MARTILL, DAVID M.
    Powiązania:
    https://bibliotekanauki.pl/articles/945956.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Instytut Paleobiologii PAN
    Tematy:
    mammalia
    eutheria
    dentition
    early cretaceous
    purbeck group
    britain
    uk
    Opis:
    Eutherian mammals (Placentalia and all mammals phylogenetically closer to placentals than to marsupials) comprise the vast majority of extant Mammalia. Among these there is a phenomenal range of forms and sizes, but the origins of crown group placentals are obscure. They lie within the generally tiny mammals of the Mesozoic, represented for the most part by isolated teeth and jaws, and there is strongly conflicting evidence from phenomic and molecular data as to the date of origin of both Eutheria and Placentalia. The oldest purported eutherians are Juramaia from the Upper Jurassic of China, and Eomaia and Acristatherium from the Lower Cretaceous, also of China. Based on dental characters and analyses of other morphological and molecular data, doubt has recently been cast on the eutherian affinities of the Chinese taxa and consequently on the date of emergence of Eutheria. Until now, the only tribosphenic mammal recorded from the earliest Cretaceous (Berriasian) Purbeck Group of Britain was the stem tribosphenidan Tribactonodon. Here we document two new tribosphenic mammals from the Purbeck Group, Durlstotherium gen. nov. and Durlstodon gen. nov., showing highly derived eutherian molar characters that support the early emergence of this clade, prior to the Cretaceous.
    Źródło:
    Acta Palaeontologica Polonica; 2017, 62, 4; 657-665
    0567-7920
    Pojawia się w:
    Acta Palaeontologica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Therian femora from the Late Cretaceous of Uzbekistan
    Autorzy:
    Chester, S.G.B.
    Sargis, E.J.
    Szalay, F.S.
    Archibald, J.D.
    Averianov, A.O.
    Powiązania:
    https://bibliotekanauki.pl/articles/20995.pdf
    Data publikacji:
    2012
    Wydawca:
    Polska Akademia Nauk. Instytut Paleobiologii PAN
    Tematy:
    Theria
    femur
    Late Cretaceous
    Uzbekistan
    Metatheria
    Eutheria
    Zhelestidae
    Zalambdalestidae
    Cretaceous
    paleontology
    Opis:
    Femora referable to metatherians and eutherians recovered from the Bissekty Formation, Dzharakuduk, Kyzylkum Desert, Uzbekistan (90 Mya), are described. Fourteen isolated specimens were sorted based on size and morphology into groups that likely correspond to the species level or higher. Groups were then tentatively assigned to taxa known from teeth, petrosals, and/or other postcrania at these localities. One distal femur of a small arboreal metatherian, and several eutherian distal femora that probably represent zhelestids and/or zalambdalestids were identified. With the exception of one proximal femur that is similar in some aspects to the zalambdalestid Barunlestes, and a previously described multituberculate specimen, all other proximal femora from the Bissekty Formation exhibit a metatherian−like morphology. The dental record currently suggests the presence of twelve eutherian species and only one metatherian at Dzharakuduk, whereas the humeral and crurotarsal evidence supports the presence of at least two or four metatherian species, respectively. Given the sample size of the proximal femora, the morphological diversity present, and the overwhelming presence of eutherians at these localities, it is highly unlikely that the overwhelming majority of proximal femora actually represent metatherians. Therefore, this sample may suggest that the metatherian proximal femoral condition is primitive for Theria and that some eutherian taxa (probably including Zhelestidae, which are dentally most abundant at these localities) retain this condition.
    Źródło:
    Acta Palaeontologica Polonica; 2012, 57, 1
    0567-7920
    Pojawia się w:
    Acta Palaeontologica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Late Cretaceous asioryctitherian eutherian mammals from Uzbekistan and phylogenetic analysis of Asioryctitheria
    Autorzy:
    Archibald, J D
    Averianov, A.O.
    Powiązania:
    https://bibliotekanauki.pl/articles/23233.pdf
    Data publikacji:
    2006
    Wydawca:
    Polska Akademia Nauk. Instytut Paleobiologii PAN
    Tematy:
    Asioryctitheria
    Eutheria
    mammal
    Late Cretaceous
    Cretaceous
    Uchkudukodon
    Uzbekistan
    Daulestes
    Mammalia
    Bulaklestes
    paleontology
    Opis:
    Four small asioryctitheres at Dzharakuduk (Turonian), Uzbekistan are Daulestes kulbeckensis (= Kumlestes olzha), D. inobservabilis (= Kennalestes? uzbekistanensis), Uchkudukodon (gen. nov.) nessovi and Bulaklestes kezbe. Uchkudukodon nessovi is one of the smallest therians (molars about 1 mm long). Lower canine is two−rooted in Uchkudukodon gen. nov. and Bulaklestes(uncertain in Daulestes). All lower premolars in all four species are double−rooted. Teeth identified as dp1, p2 and dp2 in holotype of Uchkudukodon nessovi (McKenna et al. 2000) are here identified c, p1, and p2. A phylogenetic analysis weakly supported Asioryctitheria by four synapomorphies: conular basins become distinct, the number of roots reverts to two on the lower canine, the p5 becomes longer than p4, and the metaconid on p5 is reduced and lost. Other characters diagnostic of asioryctitheres are four upper and lower premolars (arguably five upper premolars in juvenile Kennalestes), P4 has a protocone swelling or protocone, some asymmetry of the stylar shelf on M1–2, the paraconule on M1–3 is distinctly closer to the protocone than is the metaconule, protocone is of moderate height on M1–3 (70–80% of paracone or metacone height), Meckel’s groove is absent, and the mandibular foramen opens into a smaller depression on lingual side of mandibular ascending ramus. Asioryctes and Ukhaatherium are placed in Asioryctinae and along with Kennalestes are placed in Asioryctidae. Kennalestidae Kielan−Jaworowska, 1981 is a junior subjective synonym for Asioryctidae Kielan−Jaworowska, 1981. Because of uncertainties in the analysis, the positions of Daulestes, Uchkudukodon gen. nov., and Bulaklestes cannot be determined beyond referral to Asioryctitheria.
    Źródło:
    Acta Palaeontologica Polonica; 2006, 51, 2
    0567-7920
    Pojawia się w:
    Acta Palaeontologica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Counting premolars in early eutherian mammals
    Autorzy:
    Cifelli, R L
    Powiązania:
    https://bibliotekanauki.pl/articles/21321.pdf
    Data publikacji:
    2000
    Wydawca:
    Polska Akademia Nauk. Instytut Paleobiologii PAN
    Tematy:
    premolar
    Eutheria
    mammal
    Late Cretaceous
    Cretaceous
    eutherian group
    fossil mammal
    North America
    paleontology
    Opis:
    The primitive number of premolars for most eutherian groups is four. A growing number of Cretaceous taxa, however, had five. Regardless of the hypothesis used to explain the discrepancy, or what the primitive condition was, it is generally agreed that the middle (third) tooth of five-premolared taxa is the one not represented in mammals that have only four premolars. Hence the current practice of labeling the teeth as the first through fifth and the first through fourth, depending on how many teeth are observed in the jaw, results in incorrect implied homologies for the last two premolars of the series. Given the long-standing tradition of referring to the premolars as the first through fourth, for most eutherian groups, together with the uncertainties involved in interpreting the difference, the most practical solution is to refer to the disputed tooth by a neutral term, 'Px', as advocated several decades ago.
    Źródło:
    Acta Palaeontologica Polonica; 2000, 45, 2
    0567-7920
    Pojawia się w:
    Acta Palaeontologica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    New Late Cretaceous mammals from the Intertrappean beds of Rangapur, India and paleobiogeographic framework
    Autorzy:
    Rana, R S
    Wilson, G.P.
    Powiązania:
    https://bibliotekanauki.pl/articles/21414.pdf
    Data publikacji:
    2003
    Wydawca:
    Polska Akademia Nauk. Instytut Paleobiologii PAN
    Tematy:
    Eutheria
    mammal
    Gondwana
    Cretaceous
    Late Cretaceous
    tooth
    Intertrappean bed
    biogeography
    India
    Rangapur
    paleobiogeography
    paleontology
    Opis:
    A new mammal−bearing locality from the Intertrappean beds (Maastricthian) of Rangapur, Andhra Pradesh, India provides isolated teeth referable to Deccanolestes and a new eutherian, Sahnitherium rangapurensis. Dental comparisons with Cimolestes, Procerberus, and Aboletylestes do not support proposed “palaeoryctoid” affinities for Deccanolestes. Although similarities exist with Otlestes and Batodon, Deccanolestes is currently considered to be of uncertain familial affinities. Sahnitherium rangapurensis exhibits similarities to Procerberus, Paranyctoides, Alostera, Aboletylestes, and Avitotherium, but it is here placed within Eutheria incertae sedis. Despite family level taxonomic uncertainties, the new material confirms the presence of eutherians on the Indian subcontinent during the Late Cretaceous. A Eurasian connection via an early collision or some other dispersal route may explain these paleobiogeographic data, but other hypotheses are considered. In particular, paleogeographic, paleontological, and molecular systematic data hint that boreosphenidan mammals may have had wider distribution on Gondwana during the Cretaceous than previously supported.
    Źródło:
    Acta Palaeontologica Polonica; 2003, 48, 3
    0567-7920
    Pojawia się w:
    Acta Palaeontologica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    New material and reinterpretation of the Late Cretaceous eutherian mammal Paranyctoides from Uzbekistan
    Autorzy:
    Averianov, A.O.
    Archibald, J.D.
    Powiązania:
    https://bibliotekanauki.pl/articles/22276.pdf
    Data publikacji:
    2013
    Wydawca:
    Polska Akademia Nauk. Instytut Paleobiologii PAN
    Tematy:
    reinterpretation
    Late Cretaceous
    Cretaceous
    paleontology
    eutherian mammal
    mammal
    Mammalia
    Eutheria
    Paranyctoides aralensis
    Turonian Bissekty Formation
    Uzbekistan
    Opis:
    Paranyctoides aralensis, based on a partially known set of lower postcanines from the Turonian Bissekty Formation of Uzbekistan, is proposed to be a junior subjective synonym of Sailestes quadrans, itself based on an M1 from the same stratigraphic unit. As a result, the latter taxon is recombined as Paranyctoides quadrans comb. nov. Based on newly col− lected or recognized specimens, we show that this species has four lower incisors, including a procumbent i1 and a rela− tively small i4, as well as five double−rooted premolars, the smallest of which (p3) can be lost ontogenetically. The p5 of this species is premolariform, rather than molariform as previously thought based on an erroneous identification, and re− sembles North American species of Paranyctoides in the presence of a small, cingulid−like paraconid and a distal talonid cusp, as well as the absence of a metaconid. The lower molars of Paranyctoides are unique among Late Cretaceous eutherians in having a larger, lingually placed paraconid. Paranycoides probably is the sister taxon of the Late Cretaceous Zhelestidae.
    Źródło:
    Acta Palaeontologica Polonica; 2013, 58, 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:
    Paranyctoides and allies from the Late Cretaceous of North America and Asia
    Autorzy:
    Archibald, J D
    Averianov, A O
    Powiązania:
    https://bibliotekanauki.pl/articles/20198.pdf
    Data publikacji:
    2001
    Wydawca:
    Polska Akademia Nauk. Instytut Paleobiologii PAN
    Tematy:
    Paranyctoides aralensis
    Eutheria
    Late Cretaceous
    Gallolestes
    Asia
    paleobiogeography
    Sailestes
    Sailestes quadrans
    Paranyctoides sternbergi
    Mammalia
    Paranyctoides
    Gallolestes pachymandibularis
    North America
    Opis:
    Paranyctoides is represented by three named, and possibly four unnamed species in the Late Cretaceous, North America. P. aralensis from the Late Cretaceous of Dzharakuduk, Uzbekistan, belongs in this or a closely allied taxon. Lower molars have low trigonids, well-developed paraconids not appressed against metaconids, talonids on ml-2 as wide or wider than trigonids, hypoconulids often closer to entoconids than to hypoconids. Only two upper molars are known, both have comparatively narrow crowns with wide stylar shelves and stylar cusps, paracone and metacone separated, conules well developed, and protocone low. Pre- and postcingula vary from narrow in one, Sailestes quadrans, to wide in the other, Paranyctoides sp. Sailestes quadrans may be an metatherian. All known species of Paranyctoides from North America have a submolarifom ultimate premolar while Gallolestes pachymandibularis, also from North America, has molars not unlike those in Paranyctoides but may have an ultimate premolar with a molarifom trigonid. A specimen from Dzharakuduk referable to P. aralensis is suggestive of such morphology. At least P. aralensis had five premolars with the third reduced as in 'zhelestids'. These findings increase the Late Cretaceous North American/Asian ties even more for eutherians, now with 'zhelestids' and the Paranyctoides/Gallolestes clades known from both.
    Rodzaj Paranyctoides jest reprezentowany przez trzy nazwane i zapewne cztery nienazwane gatunki z późnej kredy Ameryki Północnej. P. aralensis z późnej kredy Uzbekistanu (stanowisko Dżarakuduk) należy do tego lub blisko spokrewnionego taksonu. Dolne zęby trzonowe mają niskie trygonidy, dobrze rozwinięte parakonidy nie przylegające do metakonidów, talonidy na ml-2 co najmniej tak szerokie jak trygonidy, hipokonulidy często położone bliżej entokonidów niż hipokonidów. Znane są tylko dwa górne trzonowce; oba mają dość wąską koronę z szeroką półką stylarną i guzkami stylarnymi, parakonem ddzielonym od metakonu, dobrze rozwiniętymi konulami i niskim protokonem. Pre- i postcingula są zmienne - wąskie u Sailestes quadrans, a szerokie u Paranyctoides sp. Sailestes quadrans może należeć do Metatheria. Wszystkie gatunki Paranyctoides znane z Ameryki północnej mają trzonowcokształtny ostatni przedtrzonowiec, natomiast Gallolestes pachymandibularis, także z Ameryki Północnej, ma dolne trzonowce dość podobne do trzonowców Paranyctoides, ale jego ostatni przedtrzonowiec mógł mieć trzonowcokształtny trygonid. Na morfologię taką wskazuje także okaz z Dżarakuduk, przypisywany P. aralensis. Przynajmniej P. aralensis miał pięć przedtrzonowców, przy czym trzeci jest zredukowany, jak u "zelestidów". Znaleziska te potwierdzają związki późnokredowej fauny Eutheria Ameryki Północnej i Azji, tym razem w przypadku znanych z obydwu kontynentów kladów ,,zelestidów" i Paranyctoides/Gallolestes.
    Źródło:
    Acta Palaeontologica Polonica; 2001, 46, 4
    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:
    New earliest Tiffanian [Late Paleocene] mammals from Cochrane 2, Southwestern Alberta, Canada
    Autorzy:
    Scott, C S
    Fox, R.C.
    Youzwyshyn, G.P.
    Powiązania:
    https://bibliotekanauki.pl/articles/21452.pdf
    Data publikacji:
    2002
    Wydawca:
    Polska Akademia Nauk. Instytut Paleobiologii PAN
    Tematy:
    Paleocene
    Late Paleocene
    Eutheria
    mammal
    Canada
    new combination
    Litomylus grandaletes
    Alberta
    Ptilodus gnomus
    Baiotomeus russelli
    Paleotomus junior
    fossil
    Thryptacodon orthogonius
    Paskapoo Formation
    Bessoecetor septentrionalis
    Pararyctes rutherfordi
    new species
    paleontology
    Multituberculata
    Opis:
    New mammalian fossils at Cochrane 2, Paskapoo Formation, Alberta, Canada, document five new species and two new combinations: Ptilodus gnomus sp.nov.and Baiotomeus russelli sp.nov.(Multituberculata), Thryptacodon orthogonius comb.nov.and Litomylus grandaletes sp.nov.(“Condylarthra”), Pararyctes rutherfordi sp.nov., Bessoecetor septentrionalis comb.nov., and Paleotomus junior sp.nov.(Eutheria incertae sedis).These new taxa supplement a taxonomically diverse Cochrane 2 local fauna, representing one of the most species rich Paleocene mammalian localities in the world. An earliest Tiffanian age is estimated for the locality based on the presence of the index taxa Plesiadapis praecursor, Nannodectes intermedius, and Ectocion collinus.The Cochrane 2 local fauna fails to demonstrate a decrease in species number relative to those of late Torrejonian localities from the United States, as would be predicted by current paleoclimate scenarios; the rarity of earliest Tiffanian localities in North America suggests sampling error as a partial explanation for the apparent incongruity.
    Źródło:
    Acta Palaeontologica Polonica; 2002, 47, 4
    0567-7920
    Pojawia się w:
    Acta Palaeontologica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
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