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Mesozoic tracks in new Ichnos



From: Ben Creisler
bcreisler@gmail.com


A number of new papers about dinosaurs and other Mesozoic trackmakers
in the new issue of Ichnos:


Anne S. Schulp & Mohammed Al-Wosabi (2012)
Telling Apart Ornithopod and Theropod Trackways: A Closer Look at a
Large, Late Jurassic Tridactyl Dinosaur Trackway at Serwah, Republic
of Yemen.
Ichnos 19(4):194-198
DOI:10.1080/10420940.2012.710672
http://www.tandfonline.com/doi/full/10.1080/10420940.2012.710672

A large bipedal tridactyl dinosaur trackway from the Late Jurassic of
Serwah, near Madar, Arhab district, Republic of Yemen, has been
attributed to an ornithopod trackmaker. As the distinction between
theropod and ornithopod dinosaurs can pose a challenge, we present
additional data to support and reconfirm the previous attribution.

===

Michela Contessi & Federico Fanti (2012)
Vertebrate Tracksites in the Middle Jurassic-Upper Cretaceous of South Tunisia.
Ichnos 19(4):211-227
DOI:10.1080/10420940.2012.711396
http://www.tandfonline.com/doi/full/10.1080/10420940.2012.711396

Four vertebrate tracksites from the Middle Jurassic and Upper
Cretaceous in the Tataouine basin of southern Tunisia are described.
Approximately 130 tridactyl footprints distributed over an area of 200
square meters, preserved on Callovian beds exposed at the Beni Ghedir
site, represent the oldest evidence of a dinosaur fauna in Tunisia. In
addition, three tracksites—Chenini, Ksar Ayaat, and Jebel
Boulouha—have been discovered in the Cretaceous beds of the upper
Continental Intercalaire, previously considered as a strictly marine
depositional sequence. In addition to dinosaur tracks, the Chenini
tracksite (late Albian) includes poorly preserved crocodilian tracks,
and footprints assigned to a pleurodiran turtle have been recovered at
the Ksar Ayaat locality (early Cenomanian). The Jebel Boulouha
tracksite is dominated by well-preserved tridactyl tracks referred to
small-sized theropods. Depositional settings of each tracksite have
been defined on stratigraphic and sedimentologic data, and tracks were
ascribed to different ichnocoenoses in relation to their
paleoenvironments. This new and differentiated track record gives
important information on how the fossil vertebrate fauna changed in
southern Tunisia during mid-Jurassic to mid-Cretaceous times. These
data provide a unique and useful census of tetrapod associations along
the southern margin of the peri-Mediterranean area.

===

Geoffrey Tresise & Michael J. King (2012)
History of Ichnology: The Misconceived Footprints of Rhynchosaurs.
Ichnos 19(4) : 228-237
DOI:10.1080/10420940.2012.717131
http://www.tandfonline.com/doi/full/10.1080/10420940.2012.717131


tIn 1842 Richard Owen described a Triassic reptile from Grinshill,
Shropshire, which he named Rhynchosaurus articeps. He suggested that
footprints found in the same beds were those of this fossil. However,
the footprints were characterised by a backward-pointing toe and so
were of the type now known as Rotodactylus. Huxley (1877), Woodward
(1907), and Benton (1990) have subsequently shown that the five digits
of Rhynchosaurus point forward and so could not have left these
footprints. In 1896 Beasley classified the Triassic footprints found
in Cheshire, his type D prints being those earlier assigned to
rhynchosaurs. His D1 prints were named Rhynchosauroides articeps by
Maidwell (1911). However, these D1 prints, which come from a lower
horizon in the Anisian, are consistently too small to match Owen's
fossil. Beasley's D3 form, now named Synaptichnium pseudosuchoides
Nopcsa, is more likely to represent the footprints of Rhynchosaurus
articeps, although further research and study of more complete
trackways will be necessary to clarify whether these are the
footprints of Archosauromorphs, such as rhynchosaurs or possibly those
of Archosauriformes, for example, erythrosuchids or proterosuchids.
Maidwell's Rhynchosauroides rectipes and Rhynchosauroides membranipes,
originally believed to be distinct ichnospecies, are more likely to be
synonyms, their apparent differences reflecting variations in the
substrate traversed.

===

Abdelouahed Lagnaoui, Hendrik Klein, Sebastian Voigt, Abdelkbir
Hminna, Hafid Saber, Jörg W. Schneider & Ralf Werneburg (2012)
Late Triassic Tetrapod-Dominated Ichnoassemblages from the Argana
Basin (Western High Atlas, Morocco).
Ichnos 19(4): 238-253
DOI:10.1080/10420940.2012.718014
http://www.tandfonline.com/doi/full/10.1080/10420940.2012.718014

Diverse tetrapod track assemblages with Scoyenia invertebrate traces
were discovered in the Triassic Timezgadiouine and Bigoudine
formations of the Argana Basin (Western High Atlas, Morocco). The
ichnofossils occur in alluvial plain sandstones and mudstones of the
Irohalène Member (T5) and Tadart Ouadou Member (T6) considered
Carnian-Norian in age by vertebrate remains and palynomorphs. Tetrapod
footprints are assigned to Apatopus, Atreipus-Grallator, Eubrontes
isp., Parachirotherium, cf. Parachirotherium postchirotherioides,
Rhynchosauroides ispp., and Synaptichnium isp. They can be referred to
lepidosauromorph/ archosauromorph, basal archosaur, and dinosauromorph
trackmakers. Apatopus, represented by 11 tracks of a more than 4 m
long trackway, is recorded for the first time outside of North America
and Europe. The assemblage concurs with the proposed Late Triassic age
of the track-bearing beds by the occurrence of Apatopus,
Atreipus-Grallator, and Eubrontes. If this is accepted, the
stratigraphic range of Synaptichnium and Parachirotherium, hitherto
known only from Early or Middle Triassic deposits, has to be extended
to the Carnian-Norian. The occurrence of Eubrontes in the Irohalene
Member (T5) provides further evidence for large theropods in
pre-Jurassic strata. All assemblages are referred to the Scoyenia
ichnofacies indicating continental environments with alternating wet
and dry conditions.