Temat: north america - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: A revision of 'pediomyid' marsupials from the Late Cretaceous of North America
Autorzy:: Davis, B M
Powiązania:: https://bibliotekanauki.pl/articles/23172.pdf
Data publikacji:: 2007
Wydawca:: Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:: fauna
systematics
mammal
Canada
Late Cretaceous
marsupial
Marsupialia
North America
paleontology
Opis:: “Pediomyids” are a diverse group of smallto medium−sized marsupials which comprise a significant portion of many Late Cretaceous North American mammalian faunas. Known almost exclusively from isolated teeth and jaw fragments, “pediomyids” exhibit far more diversity than any other contemporaneous group of North American mammals. This has led some to suggest that the family “Pediomyidae” is an artificial, polyphyletic assemblage composed of multiple lineages that independently acquired various traditionally−recognized “pediomyid” molar characters, such as a reduction of the anterior stylar shelf, reduction of the stylocone and a labial shift in the attachment of the cristid obliqua. The present study seeks to elucidate the interrelationships of “pediomyid” marsupials and test the monophyly of the group using cladistic methodology, including a broad sampling of Late Cretaceous North American taxa and a comprehensive set of qualitative molar characters. Results suggest that the family “Pediomyidae” and the genus “Pediomys” are both polyphyletic and are in need of systematic revision. Iqualadelphis lactea (Aquilan) appears to be unrelated to the “pediomyid” radiation, and rests as a stem taxon near the base of the cladogram. The large Aquilan Aquiladelphis nests in a trichotomy with a strictly−defined “Pediomyidae” and the enigmatic Lancian taxon Glasbius, suggesting the possibility of a distant relationship (above the familial level). Three clades are recognized within the “Pediomyidae”: a restricted Pediomys, Leptalestes gen. nov. (containing the three smallest species), and Protolambda (containing the remaining three larger species). Results suggest that “Pediomys” exiguus is a stem taxon lacking a close relationship to Pediomyidae sensu stricto, and is removed to permit recognition of the family as monophyletic. The results carry implications for the role “pediomyids” might have played in the initial North American marsupial radiation sometime prior to the Campanian, and the pattern of molar evolution throughout major Late Cretaceous lineages.
Źródło:: Acta Palaeontologica Polonica; 2007, 52, 2
0567-7920
Pojawia się w:: Acta Palaeontologica Polonica
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

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

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Skocz do pozycji: 3.

Tytuł:: New data on the dentition of the scincomorphan lizard Polyglyphanodon sternbergi
Autorzy:: Nydam, R L
Cifelli, R.L.
Powiązania:: https://bibliotekanauki.pl/articles/22344.pdf
Data publikacji:: 2005
Wydawca:: Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:: Polyglyphanodontinae
dentition
Polyglyphanodon sternbergi
Late Cretaceous
scincomorphan lizard
Squamata
lizard
North America
paleontology
Opis:: Polyglyphanodon sternbergi Gilmore, 1940 is a large−bodied lizard from the Late Cretaceous of North America distinguished by its transversely oriented, interlocking teeth. Initially the teeth of P. sternbergi were described as smooth and blade−like, but recent discoveries of new specimens from the type locality and re−examination of the original material indicate that the chisel−like teeth of P. sternbergi have small, irregular serrations along the blades. These serrations are similar in size to those found on the teeth of the modern herbivorous lizard Iguana iguana and were likely used in a similar manner to crop vegetation, but was also capable of a degree of oral food processing due to the transverse orientation and interlocking arrangement of the dentition of P. sternbergi. Additionally, the presence of transversely oriented teeth with V−shaped blades in the anterior portion of the tooth row of P. sternbergi represents an additional shared characteristic in tooth structure between P. sternbergi and Dicothodon moorensis, Bicuspidon numerosus, and Peneteius aquilonoius; all transversely−tooth polyglyphandontine lizards from the Cretaceous of North America. It appears that the unique dentitions of Polyglyphanodon sternbergi (large teeth with transverse, serrated blades) and Peneteius aquilonius (small teeth with mammal−like specializations) present by the end of the Cretaceous were derived from a bicuspid, transversely oriented precursor tooth with a V−shaped blade.
Źródło:: Acta Palaeontologica Polonica; 2005, 50, 1
0567-7920
Pojawia się w:: Acta Palaeontologica Polonica
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: A new species of saurolophine hadrosaurid dinosaur from the Late Cretaceous of the Pacific coast of North America
Autorzy:: Prieto-Marquez, A.
Wagner, J.R.
Powiązania:: https://bibliotekanauki.pl/articles/23467.pdf
Data publikacji:: 2013
Wydawca:: Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:: new species
saurolophine hadrosaurid dinosaur
dinosaur
Dinosauria
Hadrosauridae
Saurolophinae
evolution
phylogenetics
Late Cretaceous
Pacific coast
North America
Opis:: We describe and re−evaluate the systematics of specimens from the Maastrichtian Moreno Formation of California (west− ern USA) as a new species of Saurolophus, the only known genus of hadrosaurid dinosaur widespread in Asia and North America. Recognition of this new species adds substantially to the record of the taxonomic diversity of these animals west of the Rocky Mountains. The new species, Saurolophus morrisi, is diagnosed by the possession of a postorbital having or− namentation in form of wide oblique groove on jugal process. Placement of this new species in Saurolophus considerably expands the distribution of this genus, although this referral is arbitrary since phylogenetic analysis places the new species outside of the clade formed by Saurolophus osborni and Saurolophus angustirostris. However, recognition of a new, en− demic Californian hadrosaurid, especially one so closely related to both Asian and North American species, may have im− plications for future studies of both the internal biogeography of Western North America, and the history of exchange with Asia.
Źródło:: Acta Palaeontologica Polonica; 2013, 58, 2
0567-7920
Pojawia się w:: Acta Palaeontologica Polonica
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

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