A reexamination of Milosaurus mccordi, and the evolution of large body size in Carboniferous synapsids

2018 ◽  
Vol 38 (5) ◽  
pp. e1508026 ◽  
Author(s):  
Neil Brocklehurst ◽  
Jörg Fröbisch
Keyword(s):  
Body Size ◽  
Large Body ◽  
Large Body Size

A new species of the subgenus Scheloribates (Topobates) (Acari: Oribatida: Scheloribatidae) from Panama

2020 ◽  
Vol 29 (2) ◽  
pp. 278-283
Author(s):  
S.G. Ermilov
Keyword(s):  
New Species ◽  
Body Size ◽  
Leaf Litter ◽  
Related Species ◽  
Large Body ◽  
Oribatid Mite ◽  
Neotropical Region ◽  
Large Body Size ◽  
First Time ◽  
A New Species

The oribatid mite subgenus Scheloribates (Topobates) Grandjean, 1958, is recorded from the Neotropical region for the first time. A new species of this subgenus is described from the leaf litter collected in Cayo Agua Island, Panama. Scheloribates (Topobates) panamaensis sp. nov. differs from its related species by the very large body size and presence of a strong ventrodistal process on the leg femora II–IV.

scholarly journals Atmospheric Hypoxia Limits Selection for Large Body Size in Insects

PLoS ONE ◽  
2009 ◽  
Vol 4 (1) ◽  
pp. e3876 ◽  
Author(s):  
C. Jaco Klok ◽  
Jon F. Harrison
Keyword(s):  
Body Size ◽  
Large Body ◽  
Large Body Size ◽  
Selection For

scholarly journals New records of ring nematodes, Bakernema enormese n. sp. and Criconema (Nothocriconemella) graminicola Loof, Wouts & Yeates, 1997 (Nematoda: Criconematidae) from natural forests of Vietnam

2019 ◽  
Vol 41 (3) ◽  
Author(s):  
Nguyen Ngoc Chau
Keyword(s):  
New Species ◽  
Body Size ◽  
New Records ◽  
Large Body ◽  
Lateral View ◽  
The Body ◽  
Natural Forests ◽  
Large Body Size ◽  
Stylet Length ◽  
North Vietnam

Bakernema enormese sp. n., collected from rhizosphere of forest wood trees in Muong Phang, Dien Bien Province (north Vietnam) is described and illustrated. The new species is characterized by large body size and stylet. In general, this new species is close to two existing species of the same genus, B. inaequale and B. dauniense by cuticle structure in transparent membranous projections which appear in lateral view as spine-like structures on each annulus. These structure arranged into several rows along the body. In morphology, the new species differs from B. inaequale and B. dauniense  by body and stylet length, i.e. 609–842 µm and 143.5–150 µm vs. 391–578 µm and 59–74 µm for B. inaequale and vs. 391–461 µm and 65–74 µm for B. dauniense. In addition, new species can be distinguished from B. inaequale by the longer membranous projection, 8–12 vs. 6–10 µm and vagina shape, curved vs. sigmoid. From B. dauniense, the new species differs by the much longer membranous projection, 8–12 vs. 1.4–2.2 µm and less number annules between vulva and tail end (RV), 3–4 vs. 7.8 annules. The presence of Criconema (Nothocriconemella) graminicola Loof, Wouts & Yeates, in Vietnam with morphometrics, illustrators and remarks given.

scholarly journals Cope's Rule and Romer's theory: patterns of diversity and gigantism in eurypterids and Palaeozoic vertebrates

2009 ◽  
Vol 6 (2) ◽  
pp. 265-269 ◽  
Author(s):  
James C. Lamsdell ◽  
Simon J. Braddy
Keyword(s):  
Body Size ◽  
Environmental Factors ◽  
Feeding Strategy ◽  
Large Body ◽  
Large Body Size ◽  
Causal Mechanisms ◽  
Family Level ◽  
Cope’S Rule ◽  
Abiotic Environmental Factors

Gigantism is widespread among Palaeozoic arthropods, yet causal mechanisms, particularly the role of (abiotic) environmental factors versus (biotic) competition, remain unknown. The eurypterids (Arthropoda: Chelicerata) include the largest arthropods; gigantic predatory pterygotids (Eurypterina) during the Siluro-Devonian and bizarre sweep-feeding hibbertopterids (Stylonurina) from the Carboniferous to end-Permian. Analysis of family-level originations and extinctions among eurypterids and Palaeozoic vertebrates show that the diversity of Eurypterina waned during the Devonian, while the Placodermi radiated, yet Stylonurina remained relatively unaffected; adopting a sweep-feeding strategy they maintained their large body size by avoiding competition, and persisted throughout the Late Palaeozoic while the predatory nektonic Eurypterina (including the giant pterygotids) declined during the Devonian, possibly out-competed by other predators including jawed vertebrates.

Rapid growth and large body size in annual fish populations are compromised by density‐dependent regulation

2019 ◽  
Vol 95 (2) ◽  
pp. 673-678 ◽  
Author(s):  
Milan Vrtílek ◽  
Jakub Žák ◽  
Matej Polačik ◽  
Radim Blažek ◽  
Martin Reichard
Keyword(s):  
Body Size ◽  
Rapid Growth ◽  
Large Body ◽  
Fish Populations ◽  
Large Body Size ◽  
Annual Fish ◽  
Density Dependent ◽  
Density Dependent Regulation

Population size, extinction, and speciation: the fission effect in Neogene Bivalvia

Paleobiology ◽  
1986 ◽  
Vol 12 (1) ◽  
pp. 89-110 ◽  
Author(s):  
Steven M. Stanley
Keyword(s):  
Body Size ◽  
Population Size ◽  
Central America ◽  
West Coast ◽  
Large Body ◽  
Geographic Range ◽  
Ice Age ◽  
The West ◽  
Large Body Size ◽  
Species Longevity

The extinction of a species represents reduction of both geographic range and population size to zero. Most workers have focused on geographic range as a variable strongly affecting the vulnerability of established species to extinction, but Lyellian percentages for Neogene bivalve faunas of California and Japan suggest that population size is a more important variable along continental shelves. The data employed to reach this conclusion are Lyellian percentages for latest Pliocene (∼2 ma old) bivalve faunas of California and Japan (N = 245 species). These regions did not suffer heavy extinction during the recent Ice Age, and for each region the Lyellian percentage is 70%–71%.Discrepancies in population size appear to explain the following differences in survivorship to the Recent (Lyellian percentage) for three pairs of subgroups: (1) burrowing nonsiphonate species (42%) versus burrowing siphonate species (84%), which suffer less heavy predation; (2) burrowing nonsiphonate species of small size (73%) versus burrowing nonsiphonate species of large body size (96%); (3) Pectinacea (30%) versus other epifauna (71%), which suffer less heavy predation. During the Mesozoic Era, when predation was less effective in benthic settings, mean species duration for the Pectinacea was much greater (∼20 ma).Along the west coast of North and Central America, mean geographic range is greater for siphonate species of large body size than for siphonate species of small body size and greater still for pectinacean species. These ranges are inversely related to mean species longevity for the three groups, which indicates that geographic range is not of first-order importance in influencing species longevity. Species with nonplanktotrophic development neither exhibit narrow geographic ranges along the west coast of North and Central America nor have experienced high rates of extinction in California and Japan.Rates of extinction are so high for Neogene pectinaceans and nonsiphonate burrowers that without enjoying high rates of speciation these groups could not exist at the diversities they have maintained during the Neogene Period. They are apparently speciating rapidly because of the fission effect: the relatively frequent generation of new species from populations that are fragmented by heavy predation. Thus, ironically, there may be a tendency for high rates of speciation to be approximately offset by high rates of extinction. Only if mean population size for species in a particular group becomes extremely small is it likely to result in a high rate of extinction and a low rate of speciation—and hence a dramatic decline of the group. The fission effect may contribute to the general correlation in the animal world between rate of speciation and rate of extinction.

New smallest specimen of the pterosaurPteranodonand ontogenetic niches in pterosaurs

2017 ◽  
Vol 92 (2) ◽  
pp. 254-271 ◽  
Author(s):  
S. Christopher Bennett
Keyword(s):  
Body Size ◽  
Parental Care ◽  
Large Body ◽  
Taxonomic Diversity ◽  
Ecological Niches ◽  
Adult Size ◽  
Niobrara Formation ◽  
Large Body Size ◽  
Juvenile Specimen

AbstractA new juvenile specimen ofPteranodonfrom the Smoky Hill Chalk Member of the Niobrara Formation of western Kansas had an estimated wingspan in life of 1.76 m, ~45% smaller than the smallest previously known specimens, but does not differ in morphology from larger specimens. Its presence indicates that juveniles were capable of flying long distances, so it falsifies the interpretation ofPteranodonas growing rapidly to adult size under parental care before flying. Instead juveniles were precocial, growing more slowly to adult size while flying and feeding independently for several years before going to sea. Because juveniles are otherwise unknown in the Smoky Hill Chalk Member, they must have occupied different environments and ecological niches than adults; thusPteranodonexhibited ontogenetic niches. Evidence is presented that most other pterosaurs (e.g.,Rhamphorhynchus,Pterodactylus,Anhanguera) also exhibited various ontogenetic niches, which, along with their large body size, suggests that pterosaur taxonomic diversity was rather low, like that of crocodilians.

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