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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
Artykuł
Tytuł:
Comodon Kretzoi and Kretzoi, 2000 replaces Phascolodon Simpson, 1925 [Mammalia], not Phascolodon Stein, 1859
Autorzy:
Cifelli, R L
Powiązania:
https://bibliotekanauki.pl/articles/20482.pdf
Data publikacji:
2002
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Mammalia
Phascolodon gidleyi
Comodon
paleontology
Źródło:
Acta Palaeontologica Polonica; 2002, 47, 1
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:
Multituberculate mammals from near the Early-Late Cretaceous boundary, Cedar Mountain Formation, Utah
Autorzy:
Eaton, J G
Cifelli, R.L.
Powiązania:
https://bibliotekanauki.pl/articles/20067.pdf
Data publikacji:
2001
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
multituberculate
Utah
mammal
Cretaceous
Cedar Mountain Formation
Multituberculata
North America
multituberculate mammal
paleontology
Cimolodonta
Opis:
Herein we describe the oldest well-sampled multituberculate assemblage from the Cretaceous of North America. The fauna is dated at 98.37 Ma and thus approximates the Albian-Cenomanian (Early-Late Cretaceous) boundary. The multituberculate fauna is diverse. Two of the multituberculates (Janumys erebos gen. et sp. n. and an unidentified taxon) are provisionally placed among 'Plagiaulacida'. Another taxon, Ameribaatar zofiae gen. et sp. n., is of uncertain subordinal affinities. The remaining multituberculates appear to represent the advanced suborder Cimolodonta and fall within the 'Paracimexomys group'. We rediagnose Paracimexomys on the basis of the type species, P. priscus, and refer to other species as cf. Paracimexomys (including cf. P. perplexus sp. n.). A revised diagnosis is also provided for Cenomanian Dakotamys. A previously-described species from the Cedar Mountain Formation is placed in Cedaromys gen. n. as C. bestia, together with C. pawus sp. n. Bryceomys is represented in the fauna by B. intermedius sp. n. Relationships of Paracimexomys-group to later taxa remain obscure. However, Bryceomys and Cedaromys share a number of features with Cimolodontidae. Given these resemblances, together with the fact that Cimolodontidae retain certain plesiomorphies (stout lower incisor, gigantoprismatic enamel) with respect to Ptilodontoidea (to which they are commonly referred), we suggest that Cimolodontidae may have arisen from a clade within the 'Paracimexomys group', independent of ptilodontoids.
W pracy opisano najstarszy dobrze opróbowany zespół zębów wieloguzkowców (Multituberculata) z kredy Ameryki Północnej. Fauna formacji Cedar Mountain jest datowana na 98,37 mln lat temu, a więc pochodzi mniej więcej z granicy albu i cenomanu (a więc przełomu wczesnej i późnej kredy). Fauna wieloguzkowców jest zróżnicowana. Dwa z nich (Janumys erebos gen. et sp. n. oraz nieoznaczony takson) tymczasowo zaliczono do ,,Plagiaulacida". Kolejny takson, Ameribaatar zofiae gen. et sp. n., ma niejasną przynależność na szczeblu podrzędu. Wydaje się, że pozostałe wieloguzkowce reprezentują, zaawansowany podrząd Cimolodonta i należałoby je umieścić w ,,grupie Paracimexomys". Diagnoza Paracimexomys została zrewidowana na podstawie gatunku typowego, P. priscus, toteż inne gatunki potraktowano jako cf. Paracimexomys (w tym cf. P. perplexus sp. n.). Zrewidowaną diagnozę uzyskał także cenomański Dakotamys. Opisany juz wcześniej z formacji Cedar Mountain gatunek umieszczony został w nowym rdozaju Cedaromys jako C. bestia, obok C. parvus sp. n. Bryceomys reprezentowany jest w opisywanej faunie przez B. intermedius sp. n. Niejasne pozostają pokrewieństwa między grupą Paracimexomys a późniejszymi taksonami. Bryceomys i Cedaromys mają jednak wiele cech wspólnych z rodziną Cimolodontidae. Ze względu na owe podobieństwa, a także na zachowanie przez Cimolodontidae pewnych plezjomorfii (masywny dolny siekacz, gigantopryzmatczne szkliwo) nieobecnych u Ptilodontoidea (do których się je zwykle zalicza), sugerujemy, ze Cimolodontidae mogły się wyodrębnić z kladu w obrębie ,,grupy Paracimexomys", niezależnie od ptilodontoidów.
Źródło:
Acta Palaeontologica Polonica; 2001, 46, 4
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
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:
Middle Miocene carnivorans from the Monarch Mill Formation, Nevada
Autorzy:
Smith, K.
Czaplewski, N.
Cifelli, R.L.
Powiązania:
https://bibliotekanauki.pl/articles/21605.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Middle Miocene
Miocene
carnivore
Mammalia
Mustelidae
Canidae
Ailuridae
Felidae
Monarch Mill Formation
Nevada
Opis:
The lowest part of the Monarch Mill Formation in the Middlegate basin, west-central Nevada, has yielded a middle Miocene (Barstovian Land Mammal Age) vertebrate assemblage, the Eastgate local fauna. Paleobotanical evidence from nearby, nearly contemporaneous fossil leaf assemblages indicates that the Middle Miocene vegetation in the area was mixed coniferous and hardwood forest and chaparral-sclerophyllous shrubland, and suggests that the area had been uplifted to 2700–2800 m paleoaltitude before dropping later to near its present elevation of 1600 m. Thus, the local fauna provides a rare glimpse at a medium- to high-altitude vertebrate community in the intermountain western interior of North America. The local fauna includes the remains of fish, amphibians, reptiles, birds, and 25 families of mammals. Carnivorans, the focus of this study, include six taxa (three of which are new) belonging to four families. Canidae are represented by the borophagine Tomarctus brevirostris and the canine Leptocyon sp. indet. The earliest record and second North American occurrence of the simocyonine ailurid Actiocyon is represented by A. parverratis sp. nov. Two new mustelids, Brevimalictis chikasha gen. et sp. nov. and Negodiaetictis rugatrulleum gen. et sp. nov., may represent Galictinae but are of uncertain subfamilial and tribal affinity. The fourth family is represented by the felid Pseudaelurus sp. indet. Tomarctus brevirostris is limited biochronologically to the Barstovian land mammal age and thus is consistent with the age indicated by other members of the Eastgate local fauna as well as by indirect tephrochronological dates previously associated with the Monarch Mill Formation. Actiocyon parverratis sp. nov. extends the temporal range of the genus Actiocyon from late Clarendonian back to the Barstovian. The Eastgate local fauna improves our understanding of mammalian successions and evolution, during and subsequent to the Mid-Miocene Climatic Optimum (~14–17 Ma).
Źródło:
Acta Palaeontologica Polonica; 2016, 61, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dentition and relationships of the Jurassic mammal Shuotherium
Autorzy:
Kielan-Jaworowska, Z
Cifelli, R.L.
Luo, Z.
Powiązania:
https://bibliotekanauki.pl/articles/23028.pdf
Data publikacji:
2002
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
molar
mammal
dentition
China
Shuotherium
Australosphenida
Jurassic
paleontology
Opis:
The Middle Jurassic mammal Shuotherium has lower molars that possess a trigonid and talonid, but are unique in having the talonid situated in front of the trigonid, rather than behind it, as in molars of usual tribosphenic pattern. Shuotherium dongi Chow and Rich, 1982 was based on a dentary bearing seven teeth, originally interpreted as three premolars and four molars. Based on comparison with other groups of early mammals, we reinterpret the premolar–molar boundary in the holotype of S. dongi, and propose a dental formula of four (or more) premolars and three molars. The ultimate lower premolar (previously identified as the first molar) has a completely developed trigonid and no talonid or pseudo−talonid. We hypothesize that the mesial cingulid on molars of Australosphenida is a highly plausible structural antecedent to the pseudo−talonid of Shuotherium. This and other shared, derived features support a relationship of Shuotherium and Australosphenida as sister−taxa. We hypothesize that the common ancestor of Shuotherium + Australosphenida had a global distribution no younger than early Middle Jurassic, and that the respective clades diverged prior to full separation of Gondwanan and Laurasian landmasses.
Źródło:
Acta Palaeontologica Polonica; 2002, 47, 3
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Earliest Cretaceous mammals from the western United States
Autorzy:
Cifelli, R.L.
Davis, B.M.
Sames, B.
Powiązania:
https://bibliotekanauki.pl/articles/23353.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Opis:
Mammalian diversity in North America shifted significantly during the Early Cretaceous, from archaic groups dominant in the well-sampled faunas of the Late Jurassic to advanced forms (including early members of modern clades) by the Albian–Cenomanian. However, the dynamics of this transition are poorly understood, since faunas of earliest Cretaceous age are unknown. Here we describe the first fossil mammals from exposures of the Lakota Formation in the Black Hills of South Dakota, a unit correlated with the upper Berriasian–lower Barremian and positioned stratigraphically between the underlying Morrison Formation and Aptian–Albian units exposed elsewhere in North America. The mammalian fauna from the Lakota Formation is transitional with regard to the North American fossil record, representing a broad spectrum of both Jurassic and Cretaceous lineages: present are “plagiaulacidan” multituberculates allied with Late Jurassic Allodontoidea and Early Cretaceous Plagiaulacoidea; the geologically youngest dryolestoid(s) and “triconodontine” triconodontids (characteristic Late Jurassic taxa from the Morrison Formation); the oldest spalacotheriid “symmetrodont”; the first record of an amphitheriid-like stem zatherian from North America (abundant in the Middle Jurassic–earliest Cretaceous of Europe); and the oldest North American tribosphenic mammal (abundant and diverse on the continent by the end of the Early Cretaceous). Taxa making their first North American appearance in the Lakota Formation (Plagiaulacoidea, including a genus also known from the Purbeck of Britain; Spalacotheriidae, stem Zatheria, Tribosphenida) are also known from the Early Cretaceous of Western Europe, suggesting the possibility that they represent immigrants.
Źródło:
Acta Palaeontologica Polonica; 2014, 59, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Osteology, paleobiology, and relationships of the sauropod dinosaur Sauroposeidon
Autorzy:
Wedel, M J
Cifelli, R L
Sanders, R K
Powiązania:
https://bibliotekanauki.pl/articles/22230.pdf
Data publikacji:
2000
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Oklahoma
pneumatic structure
Sauroposeidon proteles
Sauroposeidon
paleobiology
Cretaceous
Antlers Formation
dinosaur
sauropod
North America
paleontology
Opis:
Sauroposeidon proteles is a large brachiosaurid sauropod recently described from the Antlers Formation (Aptian-Albian) of southeastern Oklahoma. Sauroposeidon represents the culmination of brachiosaurid trends toward lengthening and lightening the neck, and its cervical vertebrae are characterized by extensive pneumatic structures. The elaboration of vertebral air sacs during sauropod evolution produced a variety of internal structure types. We propose a new classification system for this array of vertebral characters, using computed tomography (CT) of pneumatic internal structures. Comparisons with birds suggest that the vertebrae of sauropods were pneumatized by a complex system of air sacs in the thorax and abdomen. The presence of a thoraco-abdominal air sac system in sauropods would dramatically affect current estimates of mass, food intake, and respiratory requirements. Sauroposeidon was one of the last sauropods in the Early Cretaceous of North America; sauropods disappeared from the continent by the early Cenomanian. The demise of sauropods in the Early Cretaceous of North America predates significant radiations of angiosperms, so the decline and extinction of this dinosaur group cannot be linked to changes in flora.
Sauroposeidon proteles to wielki dinozaur z rodziny brachiozaurów, opisany niedawno z formacji Antlers (apt-alb) z południowo-wschodniej Oklahomy (USA). Stanowi on kulminację widocznej u brachiozaurów tendencji do wydłużania szyi i zmniejszania jej ciężaru - kręgi szyjne odznaczają się intensywną pneumatyzacją. Rozrost worków powietrznych w kręgach szyjnych doprowadził do wytworzenia rozmaitych wariantów ich budowy wewnętrznej. Autorzy proponują nowy podział owych struktur anatomicznych, oparty na obserwacji tomograficznej spneumatyzowanych kręgów. Porównania z ptakami sugerują, że kręgi zauropodów mieściły rozbudowany system worków powietrznych obejmujących też tułów. Obecność piersiowo-brzusznych worków powietrznych oznaczałaby radykalne zmiany dotychczasowych oszacowań masy ciała, zapotrzebowania pokarmowego i wydolności oddechowej zauropodów. Zauroposejdon był jednym z ostatnich zauropodów zamieszkujących Amerykę Północną we wczesnej kredzie (we wczesnym cenomanie brak już zauropodów na tym kontynencie). Zniknięcie zauropodów z Ameryki Północnej poprzedziło większe radiacje adaptacyjne roślin okrytozalążkowych, toteż nie można wiąać upadku i zaniku tej grupy dinozaurów ze zmianami flory.
Źródło:
Acta Palaeontologica Polonica; 2000, 45, 4
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A new genus of eomyid rodent from the Miocene of Nevada
Autorzy:
Smith, K S
Cifelli, R.L.
Czaplewski, N.J.
Powiązania:
https://bibliotekanauki.pl/articles/21894.pdf
Data publikacji:
2006
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Megapeomys
Miocene
eomyid rodent
Apeomys
Rodentia
Nevada
Eomyidae
new genus
rodent
paleontology
Apeomyoides
Opis:
The description of a new genus (Apeomyoides) of eomyid rodent from the Miocene of Nevada increases the diversity of known taxa, enhances the geographic range, and extends the biochronology for the Apeomyinae (Eomyidae). Three groups of Eomyidae are known from the fossil record of North America. Of the three groups, Neogene taxa include four genera representing the Eomyinae and two genera representing the Apeomyinae; no genera of the subfamily Yoderimyinae are known from the Neogene of the continent. This diversity represents a significant reduction of eomyid taxa compared to the Paleogene, from which 17 genera of eomyines and three genera of yoderimyines are known. In Eurasia, 11 genera of eomyids occurred during the Neogene, with a few taxa that persisted until about 2 million years before present. At present, there are no known eomyids from the last 4.5 million years of the Neogene in North America. Apeomyoides savagei is referable to the subfamily Apeomyinae based on several key structures of the teeth and mandible. This new eomyid is part of the Eastgate local fauna, collected from volcanic ash deposits of the Monarch Mill Formation, Churchill County, Nevada. Apeomyoides has an occlusal pattern that shares characteristics of apeomyines from both North America (Megapeomys and Arikareeomys) and Eurasia (Apeomys and Megapeomys). The unique occlusal pattern and large size of Apeomyoides demonstrates that not all eomyids from North America were small or that their lineages decreased in size through time. Apeomyoides also may provide evidence, which challenges the hypothesis that eomyids within a single lineage from North America became more lophodont in geologically younger genera.
Źródło:
Acta Palaeontologica Polonica; 2006, 51, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
In quest for a phylogeny of Mesozoic mammals
Autorzy:
Luo, Z X
Kielan-Jaworowska, Z.
Cifelli, R.L.
Powiązania:
https://bibliotekanauki.pl/articles/23509.pdf
Data publikacji:
2002
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Monotremata
phylogenesis
Mesozoic
Boreosphenida
mammal
parsimony analysis
Mammalia
Australosphenida
Allotheria
Eutriconodonta
paleontology
Opis:
We propose a phylogeny of all major groups of Mesozoic mammals based on phylogenetic analyses of 46 taxa and 275 osteological and dental characters, using parsimony methods (Swofford 2000). Mammalia sensu lato (Mammaliaformes of some authors) are monophyletic. Within mammals, Sinoconodon is the most primitive taxon. Sinoconodon, morganucodontids, docodonts, and Hadrocodium lie outside the mammalian crown group (crown therians + Monotremata) and are, successively, more closely related to the crown group. Within the mammalian crown group, we recognize a fundamental division into australosphenidan (Gondwana) and boreosphenidan (Laurasia) clades, possibly with vicariant geographic distributions during the Jurassic and Early Cretaceous. We provide additional derived characters supporting these two ancient clades, and we present two evolutionary hypotheses as to how the molars of early monotremes could have evolved. We consider two alternative placements of allotherians (haramiyids + multituberculates). The first, supported by strict consensus of most parsimonious trees, suggests that multituberculates (but not other alllotherians) are closely related to a clade including spalacotheriids + crown therians (Trechnotheria as redefined herein). Alternatively, allotherians can be placed outside the mammalian crown group by a constrained search that reflects the traditional emphasis on the uniqueness of the multituberculate dentition. Given our dataset, these alternative topologies differ in tree−length by only ~0.6% of the total tree length; statistical tests show that these positions do not differ significantly from one another. Similarly, there exist two alternative positions of eutriconodonts among Mesozoic mammals, contingent on the placement of other major mammalian clades. Of these, we tentatively favor recognition of a monophyletic Eutriconodonta, nested within the mammalian crown group. We suggest that the “obtuse−angle symmetrodonts” are paraphyletic, and that they lack reliable and unambiguous synapomorphies.
Źródło:
Acta Palaeontologica Polonica; 2002, 47, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Systematic review of Neocaviafrom the Neogene of Argentina: Phylogenetic and evolutionary implications
Autorzy:
Madozzo-Jaen, M.C.
Perez, M.E.
Montalvo, C.
Tomassini, R.L.
Powiązania:
https://bibliotekanauki.pl/articles/21378.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Opis:
Caviidae is one of the groups of rodents with the greatest ecomorphological disparity, and with currently three known lineages: Caviinae (cuises), Dolichotinae (maras), and Hydrochoerinae (capybaras). Caviinae include small caviids represented by three extant genera (Microcavia, Cavia, and Galea) and three fossils forms (Dolicavia, Palaeocavia, and Neocavia). In Argentina, the fossil record of Caviinae is continuous and abundant since the late Miocene. Neocavia, specifically, is represented by different species recorded in the late Miocene–Pliocene. Here, we describe a new species of Neocavia from the late Miocene–early Pliocene of the Cerro Azul Formation (La Pampa Province, Argentina), and provide a re-description of already known species (Neocavia lozanoi and “Neocavia depressidens”). Also, we perform a more comprehensive review of the genus and include the Neocavia species in a phylogenetic context within Caviinae. We analyze the main patterns of the evolution of the tympanic bullae within Caviidae, and infer about a possible occasional fossorial habit of Neocavia. The morphological and phylogenetic analyses indicate that Neocavia is more closely related to Dolicavia and Microcavia than to the other Caviinae, and confirm the monophyly of the genus, with at least two clearly differentiable species. Since this study cannot confirm the systematic position and validity of “N. depressidens”, we suggest not to use this taxon as a biostratigraphic indicator.
Źródło:
Acta Palaeontologica Polonica; 2018, 63, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Vertebral morphology, dentition, age, growth, and ecology of the large lamniform shark Cardabiodon ricki
Autorzy:
Newbrey, M.G.
Siversson, M.
Cook, T.D.
Fotheringham, A.M.
Sanchez, R.L.
Powiązania:
https://bibliotekanauki.pl/articles/21003.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
morphology
dentition
age
growth
ecology
large lamniform shark
Cardabiodon ricki
Cardabiodon venator
Chondrichthyes
Lamniformes
Archaeolamna
Squalicorax
Cretaceous
Cenomanian
Turonian
Australia
Opis:
Cardabiodon ricki and Cardabiodon venator were large lamniform sharks with a patchy but global distribution in the Cenomanian and Turonian. Their teeth are generally rare and skeletal elements are less common. The centra of Cardabiodon ricki can be distinguished from those of other lamniforms by their unique combination of characteristics: medium length, round articulating outline with a very thick corpus calcareum, a corpus calcareum with a laterally flat rim, robust radial lamellae, thick radial lamellae that occur in low density, concentric lamellae absent, small circular or subovate pores concentrated next to each corpus calcareum, and papillose circular ridges on the surface of the corpus calcareum. The large diameter and robustness of the centra of two examined specimens suggest that Cardabiodon was large, had a rigid vertebral column, and was a fast swimmer. The sectioned corpora calcarea show both individuals deposited 13 bands (assumed to represent annual increments) after the birth ring. The identification of the birth ring is supported in the holotype of Cardabiodon ricki as the back-calculated tooth size at age 0 is nearly equal to the size of the smallest known isolated tooth of this species. The birth ring size (5-6.6 mm radial distance [RD]) overlaps with that of Archaeolamna kopingensis (5.4 mm RD) and the range of variation of Cretoxyrhina mantelli (6-11.6 mm RD) from the Smoky Hill Chalk, Niobrara Formation. The revised, reconstructed lower jaw dentition of the holotype of Cardabiodon ricki contains four anterior and 12 lateroposterior files. Total body length is estimated at 5.5 m based on 746 mm lower jaw bite circumference reconstructed from associated teeth of the holotype.
Źródło:
Acta Palaeontologica Polonica; 2015, 60, 4
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 46

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