Semionotiform fish from the Upper Jurassic of Tendaguru (Tanzania) (original) (raw)
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Selachians and actinopterygians from the Upper Jurassic of Tendaguru, Tanzania
Fossil Record, 2002
The first Late Jurassic selachian and actinopterygian fishes of Tendaguru in Tanzania were collected by the German-Tendaguru expedition in 1909–1913. They are represented mainly by occasional teeth of a neoselachian (Sphenodus) and several specimens of a neopterygian (Lepidotes). New material collected by the German-Tanzanian Tendaguru expedition in 2000 includes additional selachians recovered from clay stones at site Dwa 5a and isolated actinopterygian remains. At least three hybodonts (Hybodus sp., Hybodontidae indet., Lonchidion sp.) and a new neoselachian batoid are presented here. This assemblage is endemic to Tendaguru. A new batoid genus and species, Engaibatis schultzei, is described, which is the oldest record of a ray from Gondwana. The actinopterygians are represented by scarce and disarticulated scales of Lepidotes, ‘pholidophoriform’-like scales, and teleostean vertebrae. This material includes new biogeographic records for Africa. In addition, a synopsis of Jurassic fishes from Africa is presented.Die Fischfauna aus dem Oberjura von Tendaguru ist bisher nur unzureichend bekannt. Das erste Material, das von der Deutschen Tendaguru-Expedition (1909–1913) gesammelt wurde, besteht fast nur aus einigen wenigen isolierten Zähne des Haies Sphenodus und mehreren Exemplaren des Actinopterygiers Lepidotes. Neue Funde, die während der Deutsch-Tansanischen-Tendaguru-Expedition im Jahre 2000 geborgen wurden, erlauben es, mehrere Taxa zu beschreiben, die aus dem Oberjura Afrikas noch nicht bekannt waren. Anhand von Zähnen konnten mindestens drei zu den ursprünglichen Hybodontiern zählende Taxa (Hybodus sp., Hybodontidae indet., Lonchidion sp.) nachgewiesen sowie ein für Tendaguru neuer Rochen (Engaibatis schultzei n. gen. and n. sp.) festgestellt werden. Actinopterygier sind durch wenige und disartikulierte Schuppen von Lepidotes und einer ‘pholidophoriden’-ähnlichen Form sowie durch Wirbel von Teleosteern vertreten. Das neue Material gibt wichtige Hinweise auf die paläobiogeographische Verbreitung der spätjurassischen Fische. Es wird ein Überblick über die bisher bekannten jurassischen Fischfaunen Afrikas gegeben.
The trace fossil Lepidenteron lewesiensis (Mantell 1822) provides an exceptional taphonomic window to diversity of fishes as shown for the Upper Cretaceous of Poland, in the Middle Turonian–Lower Maastrichtian deposits of the Opole Trough, Miecho´w Trough, Mazury-Podlasie Homocline, and SE part of the Border Synclinorium. Lepidenteron lewesiensis is an unbranched burrow lined with small fish scales and bones, without a constructed wall. It contains scales, vertebrae, and bones of the head belonging to ten taxa of teleostean fishes: two undetermined teleosteans, six undetermined Clupeocephala, one Dercetidae, and one undetermined euteleostean. The preservation of fish remains suggests that fishes were pulled down into the burrow by an animal, probably by eunicid polychaetes.
Zootaxa, 2006
The osteology of Leptodactylus laticeps is described. This species is the most distinctive member of the pentadactylus species group, and possibly of the genus Leptodactylus, based on external morphology, skin secretions and some aspects of its life history. This paper notes some characters that differ from or were previously overlooked in, description of the Leptodactylus. These are: 1) arrangement cotylar type II, 2) sacral diapophyses expanded, 3) nasals contiguos or in contact with frontoprietals, and 4) an anterior ramus parasphenoid which can or cannot reach the palatines. Some characters could be useful for species diagnoses and/or phylogenetic studies, such as elongation of the pars facialis of maxilla, maxillary teeth found almost reaching quadratojugal or extending beyond quadratojugal, nasals with posterolateral projections very prominent, nasals almost or in contact with each other; high number of vomerine teeth, tip of palatines not acute, and an alary process of premax...
Natural History Sciences, 2011
A subfossil tooth of a dwarf Hippopotamus (Mammalia, Artiodactyla) from the Holocene of the Berivotra ouctrops (Mahajanga Basin, NW Madagascar), with remarks on the distribution of the genus in the island Abstract -We report the presence of subfossil dwarf hippopotamuses from the neighbourhood of Berivotra (Mahajanga Basin, NW Madagascar), based on an isolated premolar of Hippopotamus, tentatively referred to H. madagascariensis Guldberg, 1882 or H. lemerlei Grandidier, 1868, two of the three species of the genus known in the Malagasy fossil record. Dwarf hippopotamuses from Madagascar are Holocenic, concentrated on the central upland and near the SW coast, with the exception of a single site on the East coast. Their presence and distribution in the N is poorly documented. The new finding, in a locality about 50 km E-SE to the city of Mahajanga, represents the innermost fossil site respect to the present coast line from the NW of the island, and increases the areal distribution of the genus in the Mahajanga Province.
Homology of fin lepidotrichia in osteichthyan fishes
Lethaia, 2005
Lepidotrichia are dermal elements located at the distal margin of osteichthyan fins. In sarcopterygians and actinopterygians, the term has been used to denote the most distal bony hemisegments and also the more proximal, scale-covered segments which overlie endochondral bones of the fin. In certain sarcopterygian fishes, including the Rhizodontida, these more proximal, basal segments are very long, extending at least half the length of the fin. The basal segments have a subcircular cross section, rather than the crescentic cross section of the distal lepidotrichial hemisegments, which lack a scale cover and comprise short, generally regular, elements. In rhizodonts and other sarcopterygians, e.g. Eusthenopteron, the basal elements are the first to appear during fin development, followed by the endochondral bones and then the distal lepidotrichia. This sequence ontradicts the ‘clock-face model’ of fin development proposed by Thorogood in which the formation of endochondral bones is followed by development of lepidotrichia. However, if elongate basal ‘lepidotrichia’ are not homologous with more distal, jointed lepidotrichia and if the latter form within a distal fin-fold and the former outside this fold, then Thorogood’s ‘clock-face’ model remains valid. This interpretation might indicate that the fin-fold has been lost in early digited stem-tetrapods such as Acanthostega and Ichthyostega and elongate basal elements, but not true lepidotrichia, occur in the caudal fins of these taxa.