摘要:

A new genus and species of paracanthopterygian fish, †McConichthys longipinnis, is described from freshwater deposits of the Lower Paleocene Tullock Formation in Montana. It is the earliest known paracanthopterygian from North America. Although it is known from only a single specimen, it is nearly complete and extremely well preserved. †McConichthysis considered to be most closely related to (forming a cladistic trichotomy with) two monophyletic groups of Patterson and Rosen (in press): the Gadiformes (codfishes) and the Pediculati (a group containing Lophiiformes [anglerfishes] and Batrachoidiformes [toadfishes]). The fossil species is therefore placed in its own family (†McConichthyidae, fam. nov.).

ISSN:0272-4634    

DOI:10.1080/02724634.1988.10011692

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

A fossil catfish skull from the upper Miocene Urumaco Formation of Falcon State, Venezuela is identified asPhractocephalus hemiliopterus(Pimelodidae), a living species of the large, lowland rivers east of the Andes. This fossil provides another example, in a growing list of cases, of a long and conservative evolutionary history for an advanced South American riverine fish. The phylogenetic position ofPhractocephalusimplies that other higher level lineages of Pimelodidae had originated before six Ma. This discovery corroborates geological and other biogeographic evidence for a connection of the ancient Orinoco system to the Caribbean coast river systems of Venezuela. The fossil catfish and other large aquatic vertebrates from the same area suggest former, freshwater communities on the north coast that were much richer than modern faunas. Increasing aridity and loss of large permanent rivers in post-Miocene times has presumably caused local extinction of these communities.

ISSN:0272-4634    

DOI:10.1080/02724634.1988.10011693

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

†Astephus antiquusfrom Eocene Green Formation of Wyoming and Utah is redescribed in detail based on newly obtained material, and the position of †Astephusamong Siluriformes is reconsidered. Phylogenetic evaluation of the genus is based on descriptive information from †Astephus antiquus, the only species known by nearly complete specimens and a species that contains the type species for the genus. It was determined that Lundberg's (1970, 1975a) assessment of †Astephusas an ictalurid is the most probable interpretation of available information. Assuming that †Astephusis an ictalurid, there is strong evidence indicating that it is the sister group to a group containing all other members of the family. †Astephus calvus(Cope), the type for the genus (designated by Jordan, 1919), is considered here to be a subjective junior synonym of †Astephus antiquus(Leidy). The only other valid species recognized here as probably belonging in the genus (and probably distinct from †A. antiquus) is †A. resimusLundberg (1975a), a species known only by a single, nearly complete neurocranium.

ISSN:0272-4634    

DOI:10.1080/02724634.1988.10011694

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The relationship between size and age is central to many problems of diversity within genera of pelycosaurs and needs to be quantified before the age structure of a population can be interpreted. The degree of ossification of the limb elements provides a basis for interpreting relative age independent of size in pelycosaurs. The pattern of ossification of the humerus ofOphiacodonand of the humerus, femur, and ulna ofDimetrodonare described and stages in the development of these bones are defined. When materials from the Admiral and lower Belle Plains formations are lumped together, size correlates poorly with developmental stage. This is interpreted as a result of the presence of two species of different size within each genus. There is no evidence for a difference in the habitat selection of juveniles and adults of these genera.

ISSN:0272-4634    

DOI:10.1080/02724634.1988.10011695

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Toxochelys latiremis, a. species of Cretaceous marine turtle, is redescribed on the basis of an almost complete specimen from the Niobrara Chalk of Kansas (Upper Santonian-Lower Campanian). Two species ofToxochelys, T. latiremisCope andT. moorevillensisZangerl are recognized;T. browni(Hay),T. weeksiCollins, andT. barberi(Schmidt) are considered junior synonyms ofToxochelys latiremis. This revision extends the stratigraphic range ofT. latiremisto the Lower Maastrichtian. The geographic range of this species now extends from southern Manitoba to Arkansas.

ISSN:0272-4634    

DOI:10.1080/02724634.1988.10011696

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

A total of 166 fossil specimens, all of which have been assigned in the past to the anguid lizard subfamily Gerrhonotinae, were examined from the point of view of the derived features of the nested sets of monophyletic taxa including the subfamily and the evidence, or lack of it, for or against their inclusion in it is discussed. Of these fossils, strong evidence for the inclusion of only three was seen. It is concluded that identification of fossil specimens without sound phylogenetic information should be avoided.

ISSN:0272-4634    

DOI:10.1080/02724634.1988.10011697

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Anas[?]blanchardi(Milne-Edwards, 1863), an abundantly represented fossil duck from the lower Miocene of Saint-Gérand-le-Puy, Allier, France, has been recognized as systematically problematic in recent decades. Most recently, Cheneval (1983b) moved this fossil and closely related forms toDendrochen(Miller, 1944), a purportedly dendrocygnine genus from the lower Miocene of South Dakota. We reexaminedblanchardiusing characters shown to be of phylogenetic utility in a recent phylogenetically analysis of the Anseriformes (Livezey, 1986). This reappraisal showed thatblanchardidiverged from the rest of the Anatidae afterDendrocygnabut beforeStictonetta. A single “best” branching sequence for the included taxa—blanchardi, Thalassornis, and the Anserinae (geese and swans)—is not possible at present. Several possibly convergent characters indicate thatblanchardiwas moderately specialized for diving. We conclude thatblanchardi(and provisionally its close relativesAnas[?]consobrinaandAnas[?]natator) should be placed in a new genusMionetta, and thatDendrochenshould be listed tentatively as its sister genus. Together these two genera comprise the new subfamily Dendrocheninae, which should be listed following the Dendrocygninae.

ISSN:0272-4634    

DOI:10.1080/02724634.1988.10011698

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The fossil record of condors (Ciconiiformes: Vulturidae) in the New World is reviewed with a description of a new species ofGymnogypsfrom the early Pleistocene (Irvingtonian) of Florida. This new species shared a common ancestor with the California condor,G. californianus, and provides new information on the origin and evolution of condors in North America. A phylogenetic analysis of 39 cranial and postcranial characters indicates that the condors form a monophyletic assemblage withGymnogypsas a distinct North American genus, andVulturas a distinct South American genus. Condors probably originated in North America and may have reached South America in the mid Pliocene (Montehermosan) near the beginning of the Great American Interchange.

ISSN:0272-4634    

DOI:10.1080/02724634.1988.10011699

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

ISSN:0272-4634    

DOI:10.1080/02724634.1988.10011700

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

ISSN:0272-4634    

DOI:10.1080/02724634.1988.10011701

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor