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Endocranial cast of the Cretaceous eutherian mammal Barunlestes

100%

Kielan-Jaworowska Z., Trofimov B. A.

Acta Palaeontologica Polonica

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1986

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tom 31

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nr 1-2

An endocranial cast of the Late Cretaceous (?Middle Campanian) zalambdalestid Barunlestes butleri from the Gobi Desert in Mongolia is described and figured. The brain that produced this endocast had large, roughly pear-shaped olfactory bulbs; relatively wide lissencephalic cerebral hemispheres, strongly diverging posteriorly; the midbrain consisting of one pair of large colliculi extensively exposed on the dorsal side; relatively short and wide cerebellum. The rhinal fissure cannot be discerned with any certainty but the expansion of cerebral hemispheres suggests that the neocortex was possibly developed in this and other Cretaceous eutherian mammals.

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A new occurrence of Late Cretaceous eutherian mammal Zalambdalestes

100%

Kielan-Jaworowska Z., Trofimov B. A.

Acta Palaeontologica Polonica

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1981

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tom 26

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nr 1

3

Cranial morphology of the Cretaceous eutherian mammal Barunlestes

100%

Kielan-Jaworowska Z., Trofimov B. A.

Acta Palaeontologica Polonica

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1980

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tom 25

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nr 2

Skull and lower jaw of Late Cretaceous (?middle Campanian) eutherian zalambdalestid genus Barunlestes from the Gobi Desert in Mongolia is described and figured. It is characterized by: maxilla extending backwards along the choanae, the presphenoid with a prominent median process, very large pterygoid process of basisphenoid, a fissura Glaseri, postglenoid process extending only opposite the medial part of glenoid fossa, large promontorium, foramen arteriae stapediae, sulcus arteriae stapediae, no sulcus arteriae promontorii. Large promontoria and large olfactory bulbs indicate strong development of auditory and olfactory senses in Barunlestes. Basicranial structure of Barunlestes supports Presley's (1979) idea that the primitive mammalian morphotype with two vessels (medial internal carotid and promontory), should be revised.

4

Early Cretaceous multituberculates from Mongolia and a comparison with Late Jurassic forms

81%

Kielan-Jaworska Z., Dashzeveg D., Trofimov B. A.

Acta Palaeontologica Polonica

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1987

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tom 32

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nr 1-2

A collection of multituberculates consisting of 68 specimens (teeth or their fragments and jaw fragments) from the ?Aptian or Albian Khovboor Beds in the Gobi Desert is described. It contains four species: Eobaatar magnus gen. n., sp. n., and E. minor sp. n. (assigned to the Eobaataridae nov. in Taeniolabidoidea), Monobaatar mlmicus gen. n., sp. n., (assigned to the family incertae sedis) and Arginbaatar dimitrievae Trofimov (assigned to the Arginbaataridae in ?Plagiaulacoidea). For E. magnus and A. dimitrievae upper and lower elements are matched, E. minor is based on lower teeth, M. mimicus on upper teeth. Both the Eobaataridae and Arginbaataridae have five upper and three lower premolars. Eobaataridae has lower incisor with limited enamel band and P₄ parallel-sided with single basal cusp; it is in some respects intermediate between the Plagiaulacidae and Late Cretaceous Taeniolabidoidea. Arginbaataridae has lower incisor completely covered with enamel. It is highly specialized in the structure of P₄, which is only partly covered with enamel and rotated during ontogeny; on the other hand, it retains primitive features: upper canine and double infraorbital foramen. Both the Eobaataridae and Arginbaataridae have gigantoprismatic enamel. If gigantoprismatic enamel made its appearance only once in multituberculate evolution, one should expect that both families share a common ancestor, which would be a plagiaulacid. Some Late Jurassic and Early Cretaceous British and Late Jurassic North American multituberculates are figured for comparison. It is demonstrated that Ctenacodon has two infraorbital foramina. The systematic position of some Вolodon species is discussed.

Ograniczanie wyników

4 Acta Palaeontologica Polonica

4 Trofimov B. A.

3 Kielan-Jaworowska Z.

1 Dashzeveg D.

1 Kielan-Jaworska Z.

1 1987

1 1986

1 1981

1 1980

Endocranial cast of the Cretaceous eutherian mammal Barunlestes

A new occurrence of Late Cretaceous eutherian mammal Zalambdalestes

Cranial morphology of the Cretaceous eutherian mammal Barunlestes

Early Cretaceous multituberculates from Mongolia and a comparison with Late Jurassic forms