Gastropods from the Late Triassic Nayband Formation (Iran), their relationships to other Tethyan faunas and remarks on the Triassic gastropod body size problem

2010 ◽  
Vol 256 (2) ◽  
pp. 213-228 ◽  
Author(s):  
Alexander Nützel ◽  
Maryam Mannani ◽  
Baba Senowbari-Daryan ◽  
Mehdi Yazdi
Keyword(s):  
Body Size ◽  
Late Triassic ◽  
Size Problem ◽  
Nayband Formation

Escargots through time: an energetic comparison of marine gastropod assemblages before and after the Mesozoic Marine Revolution

Paleobiology ◽  
2011 ◽  
Vol 37 (2) ◽  
pp. 252-269 ◽  
Author(s):  
Seth Finnegan ◽  
Craig M. McClain ◽  
Matthew A. Kosnik ◽  
Jonathan L. Payne
Keyword(s):  
Body Size ◽  
Metabolic Rate ◽  
Net Primary Production ◽  
Average Energy ◽  
Late Triassic ◽  
Physiological Data ◽  
Marine Animal ◽  
Before And After ◽  
Per Capita ◽  
Mesozoic Marine Revolution

The modern structure of marine benthic ecosystems was largely established during the Jurassic and Early Cretaceous (200–100 Ma), a transition that has been termed the Mesozoic Marine Revolution (MMR). Although it has been suggested that the MMR marks an increase in the average energy consumption of marine animal ecosystems, this hypothesis has not been evaluated quantitatively. In this study, we integrate body size and abundance data from the fossil record with physiological data from living representatives to estimate mean per capita metabolic rates of tropical to subtropical assemblages of shallow-marine gastropods—a major component of marine ecosystems throughout the Meso-Cenozoic—both before and after the MMR. We find that mean per capita metabolic rate rose by ∼150% between the Late Triassic and Late Cretaceous and remained relatively stable thereafter. The most important factor governing the increase in metabolic rate was an increase in mean body size. In principle, this size increase could result from secular changes in sampling and taphonomic biases, but these biases are suggested to yield decreases rather than increases in mean size. Considering that post-MMR gastropod diversity is dominated by predators, the net primary production required to supply the energetic needs of the average individual increased by substantially more than 150%. These data support the hypothesis that benthic energy budgets increased during the MMR, possibly in response to rising primary productivity.

scholarly journals Comparative size evolution of marine clades from the Late Permian through Middle Triassic

Paleobiology ◽  
2015 ◽  
Vol 42 (1) ◽  
pp. 127-142 ◽  
Author(s):  
Ellen K. Schaal ◽  
Matthew E. Clapham ◽  
Brianna L. Rego ◽  
Steve C. Wang ◽  
Jonathan L. Payne
Keyword(s):  
Body Size ◽  
Middle Triassic ◽  
Size Reduction ◽  
Late Triassic ◽  
Early Triassic ◽  
Large Species ◽  
Late Permian ◽  
Triassic Boundary ◽  
Median Size ◽  
Permian Extinction

AbstractThe small size of Early Triassic marine organisms has important implications for the ecological and environmental pressures operating during and after the end-Permian mass extinction. However, this “Lilliput Effect” has only been documented quantitatively in a few invertebrate clades. Moreover, the discovery of Early Triassic gastropod specimens larger than any previously known has called the extent and duration of the Early Triassic size reduction into question. Here, we document and compare Permian-Triassic body size trends globally in eight marine clades (gastropods, bivalves, calcitic and phosphatic brachiopods, ammonoids, ostracods, conodonts, and foraminiferans). Our database contains maximum size measurements for 11,224 specimens and 2,743 species spanning the Late Permian through the Middle to Late Triassic. The Permian/Triassic boundary (PTB) shows more size reduction among species than any other interval. For most higher taxa, maximum and median size among species decreased dramatically from the latest Permian (Changhsingian) to the earliest Triassic (Induan), and then increased during Olenekian (late Early Triassic) and Anisian (early Middle Triassic) time. During the Induan, the only higher taxon much larger than its long-term mean size was the ammonoids; they increased significantly in median size across the PTB, a response perhaps related to their comparatively rapid diversity recovery after the end-Permian extinction. The loss of large species in multiple clades across the PTB resulted from both selective extinction of larger species and evolution of surviving lineages toward smaller sizes. The within-lineage component of size decrease suggests that only part of the size decrease can be related to the end-Permian kill mechanism; in addition, Early Triassic environmental conditions or ecological pressures must have continued to favor small body size as well. After the end-Permian extinction, size decrease occurred across ecologically and physiologically disparate clades, but this size reduction was limited to the first part of the Early Triassic (Induan). Nektonic habitat or physiological buffering capacity may explain the contrast of Early Triassic size increase and diversification in ammonoids versus size reduction and slow recovery in benthic clades.

scholarly journals The first juvenile specimens of Plateosaurus engelhardti from Frick, Switzerland: Isolated neural arches and their implications for developmental plasticity in a basal sauropodomorph

2014 ◽  
Author(s):  
Rebecca Hofmann ◽  
P. Martin Sander
Keyword(s):  
Body Size ◽  
Developmental Plasticity ◽  
Large Body ◽  
Late Triassic ◽  
Poor Correlation ◽  
Time Averaging ◽  
Large Body Size ◽  
Alternative Hypotheses ◽  
Histological Data ◽  
Multiple Species

The dinosaur Plateosaurus engelhardti is the most abundant dinosaur in the Late Triassic of Europe and the best known basal sauropodomorph. Plateosaurus engelhardti was one of the first sauropdomorph dinosaurs to display a large body size. Remains can be found in the Norian stage of the Late Triassic in over 40 localities in Central Europe (France, Germany, Greenland and Switzerland). Since the first discovery of P. engelhardti no juvenile specimens of this species had been found. Here we describe the first remains of juvenile individuals, isolated cervical and dorsal neural arches. These were separated postmortem from their respective centra because of unfused neurocentral sutures. However the specimens share the same neural arch morphology found in adults. Morphometric analysis suggests a body lengths of the juvenile indivduals that is greater than those of most adult specimens. This supports the hypothesis of developmental plasticity in Plateosaurus engelhardti that previously had been based on histological data only. Alternative hypotheses for explaining the poor correlation between ontogenetic stage and size in this taxon are multiple species or sexual morphs with little morphological variance or time-averaging of individuals from populations differing in body size.

scholarly journals The first juvenile specimens of Plateosaurus engelhardti from Frick, Switzerland: Isolated neural arches and their implications for developmental plasticity in a basal sauropodomorph

2014 ◽  
Author(s):  
Rebecca Hofmann ◽  
P. Martin Sander
Keyword(s):  
Body Size ◽  
Developmental Plasticity ◽  
Large Body ◽  
Late Triassic ◽  
Poor Correlation ◽  
Time Averaging ◽  
Large Body Size ◽  
Alternative Hypotheses ◽  
Histological Data ◽  
Multiple Species

The dinosaur Plateosaurus engelhardti is the most abundant dinosaur in the Late Triassic of Europe and the best known basal sauropodomorph. Plateosaurus engelhardti was one of the first sauropdomorph dinosaurs to display a large body size. Remains can be found in the Norian stage of the Late Triassic in over 40 localities in Central Europe (France, Germany, Greenland and Switzerland). Since the first discovery of P. engelhardti no juvenile specimens of this species had been found. Here we describe the first remains of juvenile individuals, isolated cervical and dorsal neural arches. These were separated postmortem from their respective centra because of unfused neurocentral sutures. However the specimens share the same neural arch morphology found in adults. Morphometric analysis suggests a body lengths of the juvenile indivduals that is greater than those of most adult specimens. This supports the hypothesis of developmental plasticity in Plateosaurus engelhardti that previously had been based on histological data only. Alternative hypotheses for explaining the poor correlation between ontogenetic stage and size in this taxon are multiple species or sexual morphs with little morphological variance or time-averaging of individuals from populations differing in body size.

An unusual Late Triassic nuculid bivalve with divaricate shell ornamentation, and the evolutionary history of oblique ribs in Triassic bivalves

2011 ◽  
Vol 85 (1) ◽  
pp. 22-28 ◽  
Author(s):  
Michael Hautmann ◽  
Babak Aghababalou ◽  
Leo Krystyn
Keyword(s):  
Posterior Part ◽  
Late Triassic ◽  
General Increase ◽  
New Subgenus ◽  
Extinction Event ◽  
Concentric Pattern ◽  
History Of ◽  
Nayband Formation ◽  
Mass Extinction Event ◽  
Permian Mass Extinction

The new nuculid bivalveTrigonucula(Gonionucula)aciloidesnew subgenus and species from the upper Triassic Nayband Formation of Central Iran is described.Gonionuculadiffers fromTrigonuculas.s. by the presence of oblique ribs, which either deviate from a concentric pattern at the anterior shell part, or, as in the newly described type species, consist of a complex pattern of chevron-like ribs on the central part of the flank, plus an additional set of opisthocline to more or less acline ribs on posterior part of the flank. The oblique ribs ofGonionuculaprobably aided energy-efficient burrowing, which was advantageous in competing for food resources with less efficiently burrowing detritus feeders. The number of burrowing bivalve species with oblique ribs generally rose towards the end of the Triassic, which probably reflects increasing competition at a time when most niches were re-occupied after the end-Permian mass extinction event. The fact that oblique ribs were rare in Paleozoic bivalves suggests that the level of competition was higher in post-Paleozoic biota, which is in accordance with a general increase in metabolic rates, predation pressure, and ecospace occupation in the course of the Mesozoic.

Taxonomy of the archosaur Ornithosuchus: reassessing Ornithosuchus woodwardi Newton, 1894 and Dasygnathoides longidens (Huxley 1877)

2015 ◽  
Vol 106 (3) ◽  
pp. 199-205 ◽  
Author(s):  
M. Belén von Baczko ◽  
Martín D. Ezcurra
Keyword(s):  
Body Size ◽  
Fossil Record ◽  
Size Range ◽  
Three Dimensional ◽  
The Body ◽  
Late Triassic ◽  
Current Status ◽  
Valid Species ◽  
Diagnostic Features ◽  
Sandstone Formation

ABSTRACTThe pseudosuchian archosaur Ornithosuchus, from the Lossiemouth Sandstone Formation (Late Triassic), Scotland, was the first ornithosuchid to be discovered, and the only one recorded, in the northern hemisphere. The fossil record of “Ornithosuchus longidens” is mainly based on natural moulds and, in a few cases, three-dimensional bony elements, complicating the interpretation of its anatomy. The taxonomy of this species has changed several times since the late 1800s and here we revisit its current status. The synonymy of “Dasygnathoides longidens” and Ornithosuchus woodwardi proposed by Walker (1964) is rejected, based on new interpretations of the holotype and referred specimens of “Dasygnathoides longidens”. The latter species is considered as a nomen dubium, because it lacks diagnostic features and cannot be identified beyond Pseudosuchia. As a result, Ornithosuchus woodwardi is resurrected as a valid species and its diagnosis is emended. The body size range of Ornithosuchus woodwardi is reduced to about a half, because ELGNM 1, previously considered the largest specimen of the genus, can no longer be referred to it. “Dasygnathoides longidens” cannot be assigned to any of the known archosauriforms from the Lossiemouth Sandstone Formation, but it still represents the largest predator currently known for its fauna.

scholarly journals Sandstone petrography and geochemistry of the Nayband Formation (Upper Triassic, Central Iran): Implications for sediment provenance and tectonic setting

2019 ◽  
Vol 112 (1) ◽  
pp. 20-41 ◽  
Author(s):  
Asghar Etesampour ◽  
Asadollah Mahboubi ◽  
Reza Moussavi-Harami ◽  
Nasser Arzani ◽  
Mohammad Ali Salehi
Keyword(s):  
Tectonic Setting ◽  
Active Continental Margin ◽  
Source Area ◽  
Major Elements ◽  
Upper Triassic ◽  
Late Triassic ◽  
Sediment Provenance ◽  
Provenance Areas ◽  
Nayband Formation ◽  
Southwestern Margin

AbstractThe Upper Triassic (Norian–Rhaetian) Nayband Formation is situated at the southwestern margin of Central East Iranian Microcontinent and records Eo-Cimmerian events. The formation is composed of mixed carbonate-siliciclastic deposits. This study presents information on the tectonic reconstruction and palaeoclimate of the southwestern margin of Central East Iranian Microcontinent during the Late Triassic. Petrography and modal analyses of sandstones show a variety of quartz-rich petrofacies including subarkose, lithic arkose, sublitharenite, feldspathic litharenite and litharenite. The combined modal analysis and geochemical results of major and trace elements of the sandstone samples represents mixed sedimentary, intermediate, felsic igneous rocks and moderate- to high-grade metamorphic provenance areas. The major elements and modal analyses of the Nayband Formation sandstone samples suggest an active continental margin tec-tonic settings. The palaeoclimatic conditions were sub-humid to humid with relatively low to moderate weathering in the source area which is in agreement with the palaeogeography and palaeotectonic history of southwestern margin of Central East Iranian Microcontinent during the Late Triassic.

The Mesozoic mammals

2004 ◽  
Author(s):  
T.S. Kemp
Keyword(s):  
Body Size ◽  
Large Body ◽  
Great Majority ◽  
The Body ◽  
Late Triassic ◽  
True Nature ◽  
Highly Active ◽  
Mesozoic Mammals ◽  
Life On Earth ◽  
Rats And Mice

The expression ‘Mesozoic Mammals’ refers to more than simply the mammals of that particular period of time; it also stands for an extraordinary and quite mysterious concept. From the first appearance in rocks of Late Triassic times of the small, obviously highly active, large-brained animals thought of as mammals, through the following 145 million years of life on earth culminating in the great end-Cretaceous mass extinction that saw the end of the dinosaurs, these animals remained small. Although probably far from rare at the time, the great majority of species of Mesozoic mammals were of the size of shrews, rats, and mice. A tiny handful managed to evolve to the body size of foxes or beavers, but there were no representatives at all of mammals the size of the prominent mammals of today, the herbivorous horses, antelopes, and elephants, the lions and wolves that feed upon them, or the specialist apes, whales, and anteaters. Two points highlight just how odd this restriction in body size is. The first is that the Mesozoic mammals represent no less than two-thirds of mammalian evolution from their origin to the present, so there was plenty of time for evolution, and an extensive radiation did indeed occur producing a plethora of taxa. The second is that somewhere along the line, the potential for evolving large body size certainly existed because within, metaphorically speaking, moments of the end of the Mesozoic Era, middle-sized and soon thereafter large mammals had arisen and were flourishing. Since their very earliest recognition by Dean William Buckland (Buckland 1824) from the Middle Jurassic Stonesfield Slate of Oxfordshire, Mesozoic mammals have generated controversy (Desmond 1985). Transformationists like Robert Grant denied that they were mammals, because it disturbed their accepted temporal sequence of Mesozoic reptiles preceding the exclusively Tertiary mammals. On the other hand, establishment figures like Buckland himself and Sir Richard Owen welcomed this apparent refutation of transformationism and had no doubt that they were indeed opossum-like mammals. In the end, the true nature of these fossils was accepted, and by 1871, a good number of undoubtedly Mesozoic localities had yielded undoubtedly mammalian fossils.

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