Wyniki wyszukiwania - BazTech

1

A Late Jurassic diverse ichnocoenosis from the siliciclastic Iouaride`ne Formation (Central High Atlas, Morocco)

Belvedere M., Mietto P., Ishigaki S.

Geological Quarterly

|

2010

|

Vol. 54, No 3

367-380

EN

The Late Jurassic Iouaride`ne tracksite has been studied for decades and is well-known for the reference trackway of Breviparopus taghbaloutensis. These siliciclastic flood-plain deposits bear probably more than 1500 tracks, and at least 21 trampled levels: they yield tracks of medium to very large sauropods, possible stegosaurs and theropods. The first accurate description of the footprint association made by biped trackmakers is proposed herein. More than six hundred footprints and more than a hundred trackways has been mapped and analysed; this led to the definition of four tridactyl and two tetradactyl morphotypes, mainly produced by small to very large theropods, while probable small ornithopod tracks are also present. The bipedal footprint association is dominated by medium-large theropods, which are also the most abundant type. The taxonomical attribution of the morphotypes is made difficult by the poor preservation of many specimens. Furthermore, for the most abundant theropod tracks, those with "megalosaurian" affinity, there is also a complex ichnotaxonomical situation, that makes the attributions yet more challenging; however, it was possible to recognize the great affinity of the tridactyl specimens with the Megalosauripus tracks from the Iberian Peninsula and North America. Three-dimensional models were generated from the moulds of the best-preserved specimens to render a more detailed description and for easier access to the specimens.

2

Re-examination of manus-only and manus-dominated sauropod trackways from Morocco

Ishigaki S., Matsumoto Y.

Geological Quarterly

|

2009

|

Vol. 53, No 4

441-448

EN

Manus-only and manus-dominated trackways of sauropods previously reported from the Iouaridene Basin of Morocco are relocated and re-examined. One trackway, interpreted as a manus-only trackway, was a misinterpretation of a poorly preserved trackway of a large theropod that walked in the opposite direction to that previously inferred. Two previously described manus-dominated trackways could be underprints. One previously described manus-only trackway and a newly discovered manus-only trackway could also be underprints. However, if the true im printing surface is not identified, an "underprint origin" cannot be accepted as firm evidence that the were imprinted on land, and a swimming or submerged sauropod might have left similar underprints under the contact layer. Kinematic investigations might help to reconstruct the origin of the trackway. The two manus-only trackways from the Iouaridene tracksite apparently show alternating pace lengths which suggests semi-galloping to galloping gait patterns by the trackmakers. Such a galloping gait pattern has never been reported from regular sauropod trackways, and it is unclear as to whether such a trackway pattern repre sents rapid locomotion. A partly submerged sauropod could perhaps register such galloping gait manus-only trackway patterns as a result of swimming behavior.

3

Dinosaur footprints from the Upper Cretaceous of Mongolia

Ishigaki S., Watabe M., Tsogtbaatar Kh., Saneyoshi M.

Geological Quarterly

|

2009

|

Vol. 53, No 4

449-460

EN

We report new data on 18 dinosaur footprint localities discovered in the Upper Cretaceous of the Gobi Desert of Mongolia, where we have recognized more than 20 000 footprints of dinosaurs. There are at least four types of dinosaur footprints, attributed to theropod, ornithopod, ankylosaurid and sauropod trackmakers. We have also recognized abun dant footprints of un identified trackmakers from each locality. Co existence of footprints and many skeletal remains in the same and/or nearby beds is a remarkable feature of these Mongolian sites. Analyses of dinosaur footprints and associated body fossil remains for each locality reveal that even in the same beds, the ichnofauna differ from the fauna reconstructed on the basis of body fossils of dinosaurs. The results demonstrate that dinosaur faunal assem blages reconstructed from body fossil or footprint evidence solely should be considered very carefully.