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Jurassic Forum » JURASSIC references & paper reviews » Jurassic around the world » New articles by Mike Benton available online (New Jurassic crocodile, T/J boundary extinction, etc)
New articles by Mike Benton available online
mhornДата: Sunday, 07.12.2008, 19:21 | Сообщение # 1
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Professor Mike Benton is a well-known palaeontologist in Mesozoic vertebrates


Prof. Mike Benton

Fortunately, bulk of his publications are available online for free through http://palaeo.gly.bris.ac.uk/Benton/reprints/default.html

among other topics some recent articles by Dr. Benton are related to Jurassic.
These are:

1) Hautmann M., Benton M.J., Tomashovych A. (2008) Catastrophic ocean acidification at the Triassic-Jurassic boundary // N. Jb. Geol. Paläont. Abh., 249. P.119–127; Stuttgart.

pdf: http://palaeo.gly.bris.ac.uk/Benton/reprints/2008Hautmann.pdf

Palaeobotanical and geochemical evidence indicate a sudden rise in atmospheric carbon dioxide (CO2) across the Triassic-Jurassic boundary, probably reflecting the combined effect of extensive volcanic degassing and thermal dissociation of marine gas hydrates. Using carbon isotopes as a geochemical marker, we found that the onset of the CO2 emissions coincided with an interruption of carbonate sedimentation in palaeogeographically distant regions, suggesting that hydrolysis of CO2 led to a short but substantial decrease of seawater pH that slowed down or inhibited precipitation of calcium carbonate minerals. The cessation of carbonate sedimentation correlates with a major marine extinction event, which especially affected organisms with aragonitic or high-Mg calcitic skeletons and little physiological control of biocalcification. These findings strengthen current concerns that ocean acidification from industrial CO2 release threatens biotopes that are dominated by such organisms, in particular tropical reef systems.

2) Hone D.W.E., Dyke G.J., Haden M., Benton M.J. (2008) Body size evolution in Mesozoic birds // Journal of Evolutionary Biology. V.21. P.618-624.

pdf: http://palaeo.gly.bris.ac.uk/Benton/reprints/2008Birdsize.pdf

The tendency for the mean body size of taxa within a clade to increase through evolution (Cope’s Rule) has been demonstrated in a number of terrestrial vertebrate groups. However, because avian body size is strongly constrained by flight, any increase in size during the evolution of this lineage should be limited – there is a maximum size that can be attained by a bird for it to be able to get off the ground. Contrary to previous interpretations of early avian evolution, we demonstrate an overall increase in body size across Jurassic and Cretaceous flying birds: taxon body size increases from the earliest Jurassic through to the end of the Cretaceous, across a time span of 70 Myr. Although evidence is limited that this change is directional, it is certainly nonrandom. Relative size increase occurred presumably as the result of an increase in variance as the avian clade diversified after the origin of flight: a progression towards larger body size is seen clearly within the clades Pygostylia and Ornithothoraces. In contrast, a decrease in body size characterizes the most crownward lineage Ornithuromorpha, the clade that includes all extant taxa, and potentially may explain the survival of these birds across the Cretaceous-
Palaeogene boundary. As in all other dinosaurs, counter selection for small size is seen in some clades, whereas body size is increasing overall.

3) Wilkinson L.E., Young M.T., Benton M.J. (2008) A new metriorhynchid crocodilian (Mesoeucrocodylia: Thalattosuchia) from the Kimmeridgian (Upper Jurassic) of Wiltshire, UK // Palaeontology. 51. P.1307-1333.

pdf: http://palaeo.gly.bris.ac.uk/Benton/reprints/2008Metriorhynchid.pdf

Recent revision of the marine metriorhynchid crocodilians indicates that a partial skull previously assigned to the species Metriorhynchus superciliosus and newly discovered postcranial elements from the Kimmeridge Clay of Westbury, Wiltshire belong to a new species of metriorhynchid. This material is herein described and referred to a new species of the genus Dakosaurus, characterised by four apomorphies: the size and shape of the enlarged supratemporal fossae; relatively large teeth, and half the number in relatives; the robust and unornamented cranium; and the angle that the prefrontal makes with the long axis of the skull. In a new phylogenetic analysis, Dakosaurus carpenteri sp. nov. is the basal member of a clade containing also D. maximus and D. andiniensis: it is not so short-snouted and its teeth are not so few and large as in the other two species, but the new form illustrates the ecological transition among metriorhynchids from a piscivorous diet to high-order carnivory.


Middle Jurassic - Lower Cretaceous ammonites & aptychi
 
Jurassic Forum » JURASSIC references & paper reviews » Jurassic around the world » New articles by Mike Benton available online (New Jurassic crocodile, T/J boundary extinction, etc)
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