scholarly journals Why sauropods had long necks; and why giraffes have short necks

PeerJ ◽  
2013 ◽  
Vol 1 ◽  
pp. e36 ◽  
Author(s):  
Michael P. Taylor ◽  
Mathew J. Wedel
Keyword(s):  
Body Size ◽  
Respiratory System ◽  
Cervical Vertebrae ◽  
Large Body ◽  
World Record ◽  
Large Body Size ◽  
Anatomical Features ◽  
Theropod Dinosaurs ◽  
The World ◽  
Cervical Ribs

The necks of the sauropod dinosaurs reached 15 m in length: six times longer than that of the world record giraffe and five times longer than those of all other terrestrial animals. Several anatomical features enabled this extreme elongation, including: absolutely large body size and quadrupedal stance providing a stable platform for a long neck; a small, light head that did not orally process food; cervical vertebrae that were both numerous and individually elongate; an efficient air-sac-based respiratory system; and distinctive cervical architecture. Relevant features of sauropod cervical vertebrae include: pneumatic chambers that enabled the bone to be positioned in a mechanically efficient way within the envelope; and muscular attachments of varying importance to the neural spines, epipophyses and cervical ribs. Other long-necked tetrapods lacked important features of sauropods, preventing the evolution of longer necks: for example, giraffes have relatively small torsos and large, heavy heads, share the usual mammalian constraint of only seven cervical vertebrae, and lack an air-sac system and pneumatic bones. Among non-sauropods, their saurischian relatives the theropod dinosaurs seem to have been best placed to evolve long necks, and indeed their necks probably surpassed those of giraffes. But 150 million years of evolution did not suffice for them to exceed a relatively modest 2.5 m.

scholarly journals Vertebral Adaptations to Large Body Size in Theropod Dinosaurs

PLoS ONE ◽  
2016 ◽  
Vol 11 (7) ◽  
pp. e0158962 ◽  
Author(s):  
John P. Wilson ◽  
D. Cary Woodruff ◽  
Jacob D. Gardner ◽  
Holley M. Flora ◽  
John R. Horner ◽  
...  
Keyword(s):  
Body Size ◽  
Large Body ◽  
Large Body Size ◽  
Theropod Dinosaurs

Species of the Maera-clade collected from Japan. Part 3: genera Maera Leach, 1814, Meximaera Barnard, 1969 and Orientomaera Ariyama, 2018 (addendum), with a key to Japanese species of the clade (Crustacea: Amphipoda: Maeridae)

Zootaxa ◽  
2020 ◽  
Vol 4743 (4) ◽  
pp. 451-479
Author(s):  
HIROYUKI ARIYAMA
Keyword(s):  
Body Size ◽  
Sea Of Japan ◽  
Large Body ◽  
Morphological Characters ◽  
The Sea Of Japan ◽  
Sagami Bay ◽  
Large Body Size ◽  
Japanese Species ◽  
The World ◽  
Mandibular Palp

Two species of Maera Leach, 1814, a species of Meximaera Barnard, 1969 and a species of Orientomaera Ariyama, 2018 included in the Maera clade, are described from Japan. Maera loveni (Bruzelius, 1859) was collected from the Sea of Japan and can be distinguished from its congeners by the very large body size and the gnathopod 2 palm defined by a blunt tooth bearing a strong robust seta. Maera sagamiensis sp. nov. from Sagami Bay is characterized by the presence of small notches on the coxae 1–3. Meximaera mooreana (Myers, 1989) was collected from Wakayama Prefecture and has two distinct characters: the male gnathopod 2 with wide basis and the very long uropod 3. Morphological characters of the Japanese specimens resemble well those in the literature, but the mandibular palp article 1 is projected acutely. Orientomaera incisa sp. nov. was recently collected from Wakayama Prefecture and its gnathopods 2 in both sexes bear a distinctive incision on the palm. Keys to species of Meximaera in the world and Japanese species of the Maera-clade are provided. Fifteen species included in the Maera-clade occur in Japan. 

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.

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