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A new species of the plagiaulacoid multituberculate mammal Eobaatar from the Early Cretaceous of southern Britain

100%

Sweetman S. C.

Acta Palaeontologica Polonica

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2009

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tom 54

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nr 3

373-384

Until recently, the only mammal remains to be obtained from the Early Cretaceous (Barremian, Wealden Group) Wessex Formation of the Isle of Wight, southern England were a poorly preserved left m2 and a well preserved left I2 crown representing one or possibly two plagiaulacoid multituberculate species. These were recovered in the early 1970s but despite subsequent efforts by a number of workers to recover additional Mesozoic mammal remains none were forthcoming until comprehensive bulk screening of the Wessex Formation was undertaken in a study commenced in 2002. This study resulted in the recovery of a number of new specimens representing an assemblage of at least six taxa. Among these are a well−preserved plagiaulacoid multituberculate left m1 and a similarly preserved left I3. The former permits diagnosis of a new species of eobaatarid, Eobaatar clemensisp. nov. The previously recovered left m2 is also tentatively assigned to the same taxon. In addition, another left m1, somewhat worn as a result of dietary attrition, was recently obtained by a private collector. This is of very similar morphology to the holotype of E. clemensi but slightly larger. It is undoubtedly referable to the same taxon and provides some insight into intraspecific size, and other minor morphological variations in the teeth of the new species. The I3 may also be referable to the new species, in which case it is the first well preserved I3 of a member of Eobaataridae to be fully described.

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A new albanerpetontid amphibian from the Barremian (Early Cretaceous) Wessex Formation of the Isle of Wight, southern England

63%

Sweetman S. C., Gardner J. D.

Acta Palaeontologica Polonica

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2013

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tom 58

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nr 2

A new albanerpetontid, Wesserpeton evansae gen. et sp. nov., from the Early Cretaceous (Barremian) Wessex Formation of the Isle of Wight, southern England, is described. Wesserpeton is established on the basis of a unique combination of primitive and derived characters relating to the frontals and jaws which render it distinct from currently recognized albanerpetontid genera: Albanerpeton (Late Cretaceous to Pliocene of Europe, Early Cretaceous to Paleocene of North America and Late Cretaceous of Asia); Celtedens (Late Jurassic to Early Cretaceous of Europe); and Anoualerpeton (Middle Jurassic of Europe and Early Cretaceous of North Africa). Although Wesserpeton exhibits considerable intraspecific variation in characters pertaining to the jaws and, to a lesser extent, frontals, the new taxon differs from Celtedens in the shape of the internasal process and gross morphology of the frontals in dorsal or ventral view. It differs from Anoualerpeton in the lack of pronounced heterodonty of dentary and maxillary teeth; and in the more medial loca− tion and direction of opening of the suprapalatal pit. The new taxon cannot be referred to Albanerpeton on the basis of the morphology of the frontals. Wesserpeton currently represents the youngest record of Albanerpetontidae in Britain.

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A new bernissartiid crocodyliform from the Lower Cretaceous Wessex Formation (Wealden Group, Barremian) of the Isle of Wight, southern England

51%

Sweetman S. C., Pedreira-Segade U., Vidovic S. U.

Acta Palaeontologica Polonica

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2015

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tom 60

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nr 2

A substantially complete skull of a small crocodyliform recently found on the foreshore near Yaverland on the southeast coast of the Isle of Wight, southern England is described. The locality, mode of preservation and associated matrix indicate that it is derived from one of the plant debris beds of the Lower Cretaceous Wessex Formation (Barremian, Wealden Group). The dentition, unique among crocodyliforms, serves to confirm that the specimen is referable to the, until now, monotypic family Bernissartiidae. Apomorphies, including placement of the choana entirely within the pterygoids and disposition of cranial sutures demonstrate that the Isle of Wight skull cannot be referred to Bernissartia fagesii, known from contemporaneous strata. Furthermore, these characters indicate that the specimen should not be referred to a new species of Bernissartia. It is therefore placed in a new genus and species, Koumpiodontosuchus aprosdokiti. The systematic position of Bernissartiidae, and characters used to diagnose Eusuchia, including placement of the choana(e) within the prerygoids, are discussed. Until recently this condition was thought to be restricted to Eusuchia with all non-eusuchian neosuchian crorocdiliforms possessing choanae bounded posteriorly by the pterygoids and anteriorly by the palatines. While the choana of Koumpiodontosuchus aprosdokiti gen. et sp. nov. is entirely bounded by the pterygoids it differs from the choanae of eusuchians in lacking a median septum, being anteroposteriorly elongate and in its anterior placement.

Ograniczanie wyników

3 Acta Palaeontologica Polonica

3 Sweetman S. C.

1 Gardner J. D.

1 Pedreira-Segade U.

1 Vidovic S. U.

1 2015

1 2013

1 2009

A new species of the plagiaulacoid multituberculate mammal Eobaatar from the Early Cretaceous of southern Britain

A new albanerpetontid amphibian from the Barremian (Early Cretaceous) Wessex Formation of the Isle of Wight, southern England

A new bernissartiid crocodyliform from the Lower Cretaceous Wessex Formation (Wealden Group, Barremian) of the Isle of Wight, southern England