Appendages, functional morphology and possible sexual dimorphism in a new ceratiocaridid (Malacostraca, Phyllocarida) from the Early Devonian Hunsrück Slate (south-western Germany)

2018 ◽  
Vol 4 (2) ◽  
pp. 277-292 ◽  
Author(s):  
Markus Poschmann ◽  
Alexandra Bergmann ◽  
Gabriele Kühl
Keyword(s):  
Sexual Dimorphism ◽  
Functional Morphology ◽  
Hunsrück Slate ◽  
Early Devonian ◽  
Western Germany

A new specimen of Plioplatecarpus (Mosasauridae) from the lower Maastrichtian of Alberta: comments on allometry, functional morphology, and paleoecology

1999 ◽  
Vol 36 (3) ◽  
pp. 363-369 ◽  
Author(s):  
Robert Holmes ◽  
Michael W Caldwell ◽  
Stephen L Cumbaa
Keyword(s):  
New Species ◽  
Sexual Dimorphism ◽  
Functional Morphology ◽  
Marine Environments ◽  
Similar Shape ◽  
Lower Maastrichtian ◽  
Associated Matrix ◽  
A New Species ◽  
Freshwater Environments

An incomplete specimen of the plioplatecarpine mosasaur Plioplatecarpus from the lower Maastrichtian locality of Scabby Butte (Saint Mary River Formation) closely resembles the slightly older Plioplatecarpus primaevus from Saskatchewan (Bearpaw Formation). However, quantitative and qualitative differences are observed: the vertebrae of the Scabby Butte specimen are more gracile and, although of similar shape and proportions, are relatively smaller. Since these differences cannot be readily explained by allometry or sexual dimorphism, the hypothesis that this specimen represents a new species is provisionally accepted. However, in the absence of diagnostic cranial features, a new species is not named. The morphology of the well-preserved forelimb indicates that the animal cannot be reconstructed as a subaqueous flyer, but probably used the forelimbs for paddling. The associated matrix indicates preservation in overbank deposits in a deltaic system exhibiting no evidence of open marine environments. This suggests that this mosasaur was able to exploit estuarine and freshwater environments.

scholarly journals 3D-Analysis of a non-planispiral ammonoid from the Hunsrück Slate: natural or pathological variation?

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3526 ◽  
Author(s):  
Julia Stilkerich ◽  
Trisha A. Smrecak ◽  
Kenneth De Baets
Keyword(s):  
Three Dimensional ◽  
Euphotic Zone ◽  
Type Specimen ◽  
3D Analysis ◽  
Three Dimensional Model ◽  
Hunsrück Slate ◽  
Early Devonian ◽  
Holotype Specimen ◽  
New Type

We herein examine the only known non-planispirally coiled early Devonian ammonoid, the holotype specimen of Ivoites opitzi, to investigate if the host was encrusted in vivo and if these sclerobionts were responsible for the trochospiral coiling observed in this unique specimen. To test if the presence of runner-like sclerobionts infested the historically collected specimen of Ivoites opitzi during its life, we used microCT to produce a three-dimensional model of the surface of the specimen. Our results indicate that sclerobionts grew across the outer rim (venter) on both sides of the ammonoid conch at exactly the location where the deviation from the planispiral was recognized, and where subsequent ammonoid growth would likely preclude encrustation. This indicates in vivo encrustation of the I. opitzi specimen, and represents the earliest documentation of the phenomenon. Further, this suggests that non-planispiral coiling in I. opitzi was likely pathologically induced and does not represent natural morphological variation in the species. Despite the observed anomalies in coiling, the specimen reached adulthood and retains important identifying morphological features, suggesting the ammonoid was minimally impacted by encrustation in life. As such, appointing a new type specimen—as suggested by some authors—for the species is not necessary. In addition, we identify the sclerobionts responsible for modifying the coiling of this specimen as hederelloids, a peculiar group of sclerobionts likely related to phoronids. Hederelloids in the Devonian are commonly found encrusting on fossils collected in moderately deep environments within the photic zone and are rarely documented in dysphotic and aphotic samples. This indicates that when the ammonoid was encrusted it lived within the euphotic zone and supports the latest interpretations of the Hunsrück Slate depositional environment in the Bundenbach-Gemünden area.

Geological and palaeontological information and phylogenetic hypotheses

1988 ◽  
Vol 125 (3) ◽  
pp. 207-227 ◽  
Author(s):  
K. S. W. Campbell ◽  
R. E. Barwick
Keyword(s):  
Functional Morphology ◽  
Fossil Record ◽  
Early Permian ◽  
Phylogenetic Hypothesis ◽  
Geological Data ◽  
Early Devonian ◽  
Aerial Respiration ◽  
Phylogenetic Relations ◽  
Phylogenetic Hypotheses ◽  
Physiological Characters

AbstractA number of workers have accepted the proposition that phylogenetic relations between extant organisms can be determined only by reference to the characters of those organisms. Palaeontological data, it is said, have not been useful for developing or refuting such hypotheses. This view may be tested by reference to the respiratory mechanisms of dipnoans (lungfishes) and amphibians. The structure of the heart, lungs, and circulatory systems has been used by various authors to support the view that these are sister groups. Geological data derived from stratigraphy, palaeoecology, taphonomy, geochemistry and functional morphology of primitive dipnoans is used herein to show that these organisms did not engage in aerial respiration. The first unequivocal evidence that dipnoans had become air breathers is from aestivation burrows in Early Permian rocks of the U.S.A. The Dipnoi must have evolved this capacity at some time between the Early Devonian, when the group became well established, and the Early Permian. Similarities between the respiratory systems of extant dipnoans and amphibians must be the result of convergence, or of the derivation of the Amphibia directly from the Dipnoi. The latter view is not currently accepted by any workers in the field. Thus data from the fossil record are used to demonstrate the invalid use of some neontological data for the development of a phylogenetic hypothesis. Classifications of extant organisms depending on putative shared–derived morphological or physiological characters that cannot be adequately tested for convergence by reference to fossils, must be regarded with due caution.

scholarly journals 3D-Analysis of a non-planispiral ammonoid from the Hunsrück Slate: natural or pathological variation?

2016 ◽  
Author(s):  
Julia Stilkerich ◽  
Trisha A Smrecak ◽  
Kenneth De Baets
Keyword(s):  
Three Dimensional ◽  
Euphotic Zone ◽  
Type Specimen ◽  
3D Analysis ◽  
Three Dimensional Model ◽  
Hunsrück Slate ◽  
Early Devonian ◽  
Holotype Specimen ◽  
New Type

We herein examine the only known non-planispirally coiled early Devonian ammonoid, the holotype specimen of Ivoites opitzi, to investigate if the host was encrusted in vivo and if these sclerobionts were responsible for the trochospiral coiling observed on this unique specimen. To test if the presence of runner-like sclerobionts infested the historically collected specimen of Ivoites opitzi during its life, we used microCT to produce a three-dimensional model of the surface of the specimen. Our results indicate that sclerobionts grew across the outer rim (venter) on both sides of the ammonoid conch at exactly the location where the deviation from the planispiral was recognized, and where subsequent ammonoid growth would likely preclude encrustation. This indicates in vivo encrustation of the I. opitzi specimen, and represents the earliest documentation of the phenomenon. Further, this suggests that non-planispiral coiling in I. opitzi was pathologically induced and does not represent natural morphological variation in the species. Despite the observed anomalies in coiling, the specimen reached adulthood and retains important identifying morphological features, suggesting the ammonoid was minimally impacted by encrustation in life. As such, appointing a new type specimen – as suggested by some authors – for the species is not necessary. In addition, we identify the sclerobionts responsible for modifying the coiling of this specimen as hederelloids, a peculiar group of sclerobionts likely related to phoronids. Hederelloids in the Devonian are commonly found encrusting on fossils collected in moderately deep environments within the photic zone and are rarely documented in dysphotic and aphotic samples. This indicates that when the ammonoid was encrusted it lived within the euphotic zone and supports the latest interpretations of the Hunsrück Slate depositional environment.

Plectodiscus discoideus (Rauff): A redescription of a chondrophorine from the early devonian hunsrück Slate, West Germany

PalZ ◽  
1983 ◽  
Vol 57 (1-2) ◽  
pp. 39-68 ◽  
Author(s):  
Ellis L. Yochelson ◽  
Wilhelm Stürmer ◽  
George O. Stanley
Keyword(s):  
West Germany ◽  
Hunsrück Slate ◽  
Early Devonian

scholarly journals Did the thylacine violate the costs of carnivory? Body mass and sexual dimorphism of an iconic Australian marsupial

2020 ◽  
Vol 287 (1933) ◽  
pp. 20201537
Author(s):  
Douglass S. Rovinsky ◽  
Alistair R. Evans ◽  
Damir G. Martin ◽  
Justin W. Adams
Keyword(s):  
Sexual Dimorphism ◽  
Body Mass ◽  
Functional Morphology ◽  
Three Dimensional ◽  
Accurate Estimate ◽  
Predator Prey ◽  
Volumetric Model ◽  
Carnivorous Marsupial ◽  
Australian Marsupial ◽  
Average Adult

The relative body masses of predators and their prey strongly affect the predators' ecology. An accurate estimate of the mass of an extinct predator is therefore key to revealing its biology and the structure of the ecosystem it inhabited. Until its extinction, the thylacine was the largest extant carnivorous marsupial, but little data exist regarding its body mass, with an average of 29.5 kg the most commonly used estimate. According to the costs of carnivory model, this estimate predicts that thylacines would have focused on prey subequal to or larger than themselves; however, many studies of their functional morphology suggest a diet of smaller animals. Here, we present new body mass estimates for 93 adult thylacines, including two taxidermy specimens and four complete mounted skeletons, representing 40 known-sex specimens, using three-dimensional volumetric model-informed regressions. We demonstrate that prior estimates substantially overestimated average adult thylacine body mass. We show mixed-sex population mean (16.7 kg), mean male (19.7 kg), and mean female (13.7 kg) body masses well below prior estimates, and below the 21 kg costs of carnivory threshold. Our data show that the thylacine did not violate the costs of carnivory. The thylacine instead occupied the 14.5–21 kg predator/prey range characterized by small-prey predators capable of occasionally switching to relatively large-bodied prey if necessary.

scholarly journals Homology and Functional Morphology of the Sexual Dimorphism in the Antenna of Sclerocypris Sars, 1924 (Crustacea, Ostracoda, Megalocypridinae)

1987 ◽  
Vol 57 (2) ◽  
pp. 183-190 ◽  
Author(s):  
Koen Martens
Keyword(s):  
Sexual Dimorphism ◽  
Functional Morphology ◽  
Larval Morphology ◽  
Male Antenna ◽  
Male Condition

The sexual dimorphism in the chaetotaxy of the antenna in various species of Sclerocypris is studied and described. Relying on larval morphology, a homology between the patterns in the two sexes is deduced and a suitable nomenclature for the apomorphic male condition is proposed. The differences observed are in all probability related to the function of the male antenna during copulation.

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