摘要:

A virtually complete skeleton of the pinnipedEnaliarctos mealsiis described from the Pyramid Hill Sandstone Member of the Jewett Sand (late Oligocene or early Miocene) in central California. Skeletal evidence supports the sister group relationship of ursids and pinnipeds and the monophyly of pinnipeds. The structure of the vertebral column, especially the long transverse processes on the lumbar vertebrae and loose-fitting zygapophyses, indicates that the spine was capable of considerable flexion and extension. The limbs, modified as flippers with strongly developed bony processes and expanded areas for muscle attachment, provide evidence of their use in both aquatic and terrestrial locomotion.

ISSN:0272-4634    

DOI:10.1080/02724634.1990.10011803

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Middle and Late Pleistocene representatives of the genusSmilodonin South and North America are here assigned to different species. The South AmericanS. populator, which existed east of the Andes, is distinguished from the North AmericanS. fatalisby the following characters: generally larger size, narrower skull with cranial part elongated relative to facial part, high nasals resulting in nearly straight dorsal profile, marked angle between mastoid and occipital plane, more “graviportal” limb bones, and extremely massive metapodials. Most differences are shown to arise from changes in allometric growth pattern; the difference is on a par with that between other valid and accepted species of carnivores. The detection of sexual dimorphism, the proper use of the ratio diagram, and subspecific versus specific differentiation are discussed.

ISSN:0272-4634    

DOI:10.1080/02724634.1990.10011804

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

ISSN:0272-4634    

DOI:10.1080/02724634.1990.10011805

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The description of two previously unknown petrosal specimens ofArsinoitheriumhighlights a number of derived ungulate characteristics. A phylogenetic analysis based on ungulate periotic anatomy implies that perissodactyls, sirenians, proboscideans, and arsinoitheres are united by the absence of a subarcuate fossa, derived course of the facial nerve, and open stylomastoid foramen. The form of the fenestra ovalis and fenestra rotundum links proboscideans, sirenians, and arsinoitheres. Absence of a discrete cochlea aqueduct implies a sister-group relationship between arsinoitheres and proboscideans. Artiodactyls are primitive in all respects except for the complete enclosure of the epitympanic recess by the tegmen tympani. The phylogenetic position of hyracoids is equivocal with the possibility of amastoidy and absence of promontorial grooves being independently derived.

ISSN:0272-4634    

DOI:10.1080/02724634.1990.10011806

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Ten isolated petrosals of Late Cretaceous marsupials belonging to three types—A, B, and C—are described from the Lance Formation of Wyoming and the Bug Creek Anthills of Montana. These are compared with ear regions of other Mesozoic and Recent mammals in a cladistic analysis of 24 petrosal characters among ten taxa. A clade comprising marsupials, eutherians, andVincelestesfrom the Early Cretaceous of Argentina is supported by five synapomorphies of the ear region—coiled cochlea, perilymphatic duct enclosed in an osseous canal, post-promontorial tympanic sinus present, caudal tympanic process of the petrosal present behind stapedius fossa, and lateral wall of fossa incudis formed by squamosal. Marsupialia is diagnosed by four synapomorphies of the ear region—stapedial artery absent in adult, prootic canal reduced and with intramural opening, prootic sinus within deep sulcus between petrosal and squamosal, and sphenoparietal emissary vein present. Eutheria is also diagnosed by four synapomorphies of the ear region—fenestra vestibuli elliptical, prootic canal absent, prootic sinus absent in adult, and capsuloparietal emissary vein present.

ISSN:0272-4634    

DOI:10.1080/02724634.1990.10011807

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Two new species of washakiin omomyids occur in deposits of early Bridgerian age.Shoshonius bowni, sp. nov., from the Aycross Formation, Absaroka Range, Wyoming, differs fromS. cooperiin having enlarged conules on the upper molars and a second metaconule, features convergent withWashakius insignis. Washakius izetti, sp. nov., from the Green River Formation, Piceance Creek Basin, Colorado, is the most primitive known species ofWashakius, showing incipient development of features present in the laterW. insignisandW. woodringi. Washakius, cf.W. izettioccurs in the early Bridgerian of the Huerfano Basin.W. izettiis closely related toUtahia kayi, a. washakiin possibly related toStockia. Hemiacodon, sometimes included in the Washakiini, is probably more closely related to the Omomyini.Stockiais distinct fromOmomysand is questionably included in the Washakiini, of whichLoveinais the stem taxon. More advanced washakiins form two groups between which there was significant parallel evolution in dental morphology. One group includesWashakius, Dyseolemur, Utahia, and possiblyStockia, and is characterized by development of an open talonid notch before the consistent appearance of metastylids. The other group consists ofShoshonius, where the establishment of metastylids preceded the full opening of the talonid basins.

ISSN:0272-4634    

DOI:10.1080/02724634.1990.10011808

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

A new genus of trematopsid amphibian, based upon the type ofAcheloma priceiOlson, 1941, and in the new combinationPhonerpeton pricei, gen. nov., is described from material collected from the Lower Permian redbeds of Texas.Phonerpetonis interpreted as a small, lightly built, terrestrially adapted carnivore, and is distinguished by the presence of a semilunar curvature of the squamosal, domed parietals, an unossified sphenethmoid, long and slender mid-dorsal ribs, and a radius with a semicircular cross section.

ISSN:0272-4634    

DOI:10.1080/02724634.1990.10011809

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Alligatorium depereti, a species of the family Atoposauridae from the Upper Berriasian-Lower Valanginian (Early Cretaceous) of Spain, has neither been revised nor redescribed since the first decade of this century. In the present paper we propose thatAlligatorium deperetibe transferred to a new genus,Montsecosuchus, on the basis of a detailed description following recent preparation of the holotype specimen. The main autapomorphic features ofMontsecosuchusare: cranial length less than one-half that of the presacral region, domed occiput (=dolichocephalous), parieto-squamosal suture ungrooved, and retroarticular process caudally projected and dorsally recurved.Montsecosuchushas three sacral vertebrae, a trait perhaps shared withAlligatorellus. The iliac blade exhibits a rounded anterior border. This feature could be an autapomorphy ofMontsecosuchusor, on the basis of the available data concerning the closest sister groups of Atoposauridae, a probable convergence. Finally, the forelimb ofMontsecosuchusdiffers from that of other Atoposauridae in having a relatively short zeugopod (the radius especially), another probable autapomorphic trait.

ISSN:0272-4634    

DOI:10.1080/02724634.1990.10011810

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The remains of the omithomimid dinosaurArchaeomithomimus asiaticusfrom the Upper Cretaceous of the People's Republic of China are described and comparisons made with the bones ofElaphrosaurus, Gallimimus, Struthiomimus, Ornithomimus, Dromiceiomimus, Deinocheirus, andAllosaurus. The diagnosis of the Ornithomimidae of Russell (1972) is expanded to include the characters ofElaphrosaurusandArchaeomithomimus. Some of the remains from the Arundel Formation of Maryland that have been referred toArchaeomithomimus affinisare probably ornithomimid but are generically and specifically indeterminate.

ISSN:0272-4634    

DOI:10.1080/02724634.1990.10011811

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

ISSN:0272-4634    

DOI:10.1080/02724634.1990.10011812

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor