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Post by Gorilla king on Jun 23, 2021 12:16:04 GMT -5
Elbow-joint morphology as a guide to forearm function and foraging behaviour in mammalian carnivores
Abstract
"Among the hunting strategies employed by members of the order Carnivora (Mammalia), two, stalk and ambush and sustained pursuit, are particularly prevalent among larger species of the order. It has been difficult to identify morphological traits that support this distinction and ecological observations have shown that most carnivorans adopt a continuum of strategies, depending on available habitat and prey. In this paper, the shape of the distal humerus articulation is analysed, with the aim of exploring the use of the forelimb in prey procurement, and as a guide to such behaviour among fossil carnivorans. The results suggest that manual manipulation and locomotion are conflicting functions. Elbow-joint morphology supports a division between grapplers (i.e. ambushers) and nongrapplers (i.e. pursuers). Joints of the former are characterized by being relatively wide and the latter, by being relatively narrow and box-like with pronounced stabilizing features. At intermediate and large body sizes, carnivorans show a pattern suggesting mutually exclusive feeding strategies that involve either grappling with prey or sustained pursuit. The former allows for large body sizes, such as pantherine felids and ursids; the latter includes species of only moderate size, such as hyenids and canids. Elbow-joint morphology is closely linked to phylogeny, but the morphology of the cheetah converges with that of nongrapplers, showing that strong selective forces may override the phylogenetic component. Two taxa of giant mustelids from the Miocene were analysed to test whether this sort of analysis is applicable to carnivorans of the past. The African Late Miocene species Ekorus ekakeran has a joint morphology comparable to that of modern-day nongrapplers. Two joint morphologies were found in the North American Late Oligocene-Early Miocene Megalictis ferox. The first morphology is comparable to that of modern pantherine cats and the second forms an intermediate between grapplers and nongrapplers that is not present in the modern carnivoran fauna."
1. Polar Bear: -7.999 2. Brown Bear: -7.045 3. Spectacled Bear: -6.517 4. Giant Panda: -6.034 5. American Black Bear: -5.521 6. Sloth Bear: -4.447
Lion: -0.531 Jaguar: -1.713 Leopard: +1.072 Cougar: +1.633 Grey Wolf: +10.470 Spotted Hyena: +8.006 Wolverine: -1.356 American Badger: -0.859
academic.oup.com/zoolinnean/article/142/1/91/2691231
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Post by Gorilla king on Jun 23, 2021 12:24:59 GMT -5
Differential scaling of the long bones in the terrestrial carnivora and other mammals
Abstract
"We measured the lengths and diameters of four long bones from 118 terrestrial carnivoran species using museum specimens. Though intrafamilial regressions scaled linearly, nearly all intraordinal regressions scaled non-linearly. The observed non-linear scaling of bone dimensions within this order results from a systematic decrease in intrafamilial allometric slope with increasing body size. A change in limb posture (more upright in larger species) to maintain similar peak bone stresses may allow the nearly isometric scaling of skeletal dimensions observed in smaller sized mammals (below about 100 kg). However, strong positive allometry is consistently observed in a number of large terrestrial mammals (the largest Carnivora, the large Bovidae, and the Ceratomorpha). This suggests that the capacity to compensate for size increases through alteration of limb posture is limited in extremely large-sized mammals, such that radical changes in bone shape are required to maintain similar levels of peak bone stress"
ML-diameters of all four major limb bones
1. Sloth Bear - 42.42% 2. Brown Bear - 40.97% 3. Asian Black Bear - 40.23% 4. Polar Bear - 39.81% 5. Sun Bear - 39.38% 6. Giant Panda - 37.43% 7. American Black Bear - 35.60% (should definitely be higher as the individuals used in the sample were rather small) 8. Spectacled Bear - 34.64%
Jaguar - 40.38% River Otter - 40.25% American Badger - 37.13% Lion - 36.86% Spotted Hyena - 36.55% Leopard - 36.29% Cougar - 35.66% Tiger - 34.35% Grey Wolf - 30.34% Cheetah - 28.41%
www.researchgate.net/publication/20806549_Differential_scaling_of_the_long_bones_in_the_terrestrial_carnivora_and_other_mammals
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Post by Gorilla king on Jun 23, 2021 12:30:44 GMT -5
Bite forces and evolutionary adaptations to feeding ecology in carnivores (Ecology)
Abstract
"The Carnivora spans the largest ecological and body size diversity of any mammalian order, making it an ideal basis for studies of evolutionary ecology and functional morphology. For animals with different feeding ecologies, it may be expected that bite force represents an important evolutionary adaptation, but studies have been constrained by a lack of bite force data. In this study we present predictions of bite forces for 151 species of extant carnivores, comprising representatives from all eight families and the entire size and ecological spectrum within the order. We show that, when normalized for body size, bite forces differ significantly between the various feeding categories. At opposing extremes and independent of genealogy, consumers of tough fibrous plant material and carnivores preying on large prey both have high bite forces for their size, while bite force adjusted for body mass is low among specialized insectivores. Omnivores and carnivores preying on small prey have more moderate bite forces for their size. These findings indicate that differences in bite force represent important adaptations to and indicators of differing feeding ecologies throughout carnivoran evolution. Our results suggest that the incorporation of bite force data may assist in the construction of more robust evolutionary and palaeontological analyses of feeding ecology."
BFQ at the canine tips
1. Sun Bear - 160.5 at the canine tips 2. Giant Panda - 151.4 at the canine tips 3. Spectacled Bear - 103.1 at the canine tips 4. Brown Bear - 99.3 at the canine tips 5. Asian Black Bear - 95.6 at the canine tips 6. Polar Bear - 92.3 at the canine tips 7. American Black Bear - 77.2 at the canine tips 8. Sloth Bear - 59.9 at the canine tips
Tiger - 130.4 at the canine tips Lion - 123.8 at the canine tips Jaguar - 118.6 at the canine tips Leopard - 119.8 at the canine tips Cougar - 118.8 at the canine tips Cheetah - 72.7 at the canine tips Grey Wolf - 127.3 at the canine tips African Wild Dog - 131.1 at the canine tips Spotted Hyena - 99.6 at the canine tips Wolverine - 104.6 at the canine tips
www.academia.edu/239888/Bite_forces_and_evolutionary_adaptations_to_feeding_ecology_in_carnivores_Ecology_
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Post by Gorilla king on Jun 23, 2021 12:37:48 GMT -5
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Post by Gorilla king on Jun 23, 2021 12:40:51 GMT -5
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Post by Gorilla king on Jun 23, 2021 12:41:54 GMT -5
BEARS HAVE MORE POWERFUL BICEPS MUSCLES THAN THOSE OF FELIDS:
"Among these traits, the intertubercular groove morphology has interesting functional implications: the tendon of the muscle biceps brachii runs into this groove, with the transversal humeral ligament (developed between both the greater and the lesser tubercles) keeping the tendon in place inside the groove (Evans 1993; Barone 2010). As described previously, the shape of the intertubercular groove is similar in canids, felids, and amphicyonids in general (thus including M. anceps), it being markedly different from that of ursids, which have a much more closed, canal-like groove (Fig. 6). Taylor (1974) associated this character with both the power of the muscle biceps brachii and the degree of usage: a clearly defined intertubercular groove, such as that of ursids, would allow a better control of movements, and probably a powerful muscle. According to Taylor (1974) the nandiniid Nandinia binotata, which shows an ursid-like groove, employs this muscle to a much greater degree than the viverrid Civettictis civetta (with a much more open groove) and this would be related to the greater climbing ability of the former."
www.researchgate.net/publication/264931438_Comparative_Anatomy_of_the_Shoulder_Region_in_the_Late_Miocene_Amphicyonid_Magericyon_anceps_Carnivora_Functional_and_Paleoecological_Inferences
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Post by Gorilla king on Jun 23, 2021 12:42:39 GMT -5
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Post by Gorilla king on Jun 23, 2021 12:44:29 GMT -5
PERSONAL COMMUNICATION THAT RORQUAL GOT FROM DALE MIQUELLE:
IN REGARDS TO STRENGTHS, THE BIGCATS HAVE REDUCED COLLARBONES WHEN COMPARED TO UNGULATES AND BEARS, WHICH INCREASES FLEXIBILITY AND SPEED, WHILE COMPROMISING ULTIMATE STRENGTH POTENTIAL.
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Post by Gorilla king on Jun 24, 2021 19:13:37 GMT -5
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Post by Gorilla king on Jun 24, 2021 19:22:33 GMT -5
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Post by Gorilla king on Jul 13, 2021 17:46:47 GMT -5
Front limbs
Of all the morphologic features that typify bears, the front limbs and associated skeletal infrastructure are the most distinctive. They are also diagnostic of the bear life strategy (see Life strategy). No other terrestrial vertebrate of its size--certainly no other large carnivore--has front limbs that are as flexible, powerfully built, and mounted with such dexterous paws. Nor do any comparable-sized carnivores have such out-sized claws...claws which are clearly "designed" to be powered by the muscular arms and shoulders to either climb trees, extract food from a durable matrix (i.e., dig), or grapple with and subdue large prey such as seals, moose, and elk. What follows is a summary of the evidence produced over the years elaborating on and substantiating the preceding thumbnail sketch. You will have to forgive me for the abundance that follows, but it is reflective of the extent to which I see this aspect of bear morphology as key to understanding the overall bear life strategy--as well as niche.
The results at left come from a seminal paper published by Alberto Martin-Serra and his colleagues in 2014. His analyses delve into patterns of variation in post-cranial skeletal structure among carnivores. Some of the results are relatively arcane, as is often the case in morphology. But the overall results insofar as bears are concerned are pretty straight-forward.
Each of the graphs at left represents major coordinated trends in the shape of two important front-limb bones--the radius at top, and the scapula (or shoulder blade) in the bottom two graphs. This variation is after accounting for the effects of body size, as such. Each dot represents an individual specimen, with those of bears denoted by brown dots and those of all other carnivore species by gray dots. The bones illustrated along each axis portray the shape that is associated with extreme values along each gradient. "PC I" invariably represents the dominant theme of variation, "PC II" the secondary theme, and "PC III" the tertiary theme. The typifying characteristics of the quadrant occupied by the bear specimens are described in the corresponding corner.
The key results here are: first, that bears are clearly differentiated from all other carnivores when it comes to shape of the radius and scapula, especially so for the scapula; and, second, that the main differentiating theme is captured by the term "robust." In other words, even after controlling for the effects of body size, bears have stout and strongly built front limb bones, most remarkably so in the case of the scapula. Which implies that these robust bones are built to support disproportionately strong front-limb muscles. Which further implies that the "bear niche" is typified by activities that require deployment of strong front legs anchored to a strong scapula.
Dexterity
Olecranon process of the ulna
The figure above again draws on the work of Martin-Serra, but focused here on the shape of the ulna. This shape-related variation is what remains after accounting for the effects of body size. As you can see, the bears (dark brown dots) are differentiated from all other carnivores primarily by the shape of the olecarnon process (along PC II). More specifically, bears have relatively the shortest and most rearward (or caudal)-facing process, which signifies a less important role for the triceps (versus the biceps)...which signifies, in turn, a design to hold up under various load stresses rather than to efficiently move about over long distances.
Running speed
Claws
www.allgrizzly.org/front-limbs
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Post by Gorilla king on Jul 13, 2021 17:52:58 GMT -5
Intelligence
A commentary on "intelligence"
Intelligence is a notoriously tricky phenomenon to reckon. One way to assess intelligence is perhaps in terms of how well an individual--or species--is able to upload and process information, contextualize it, store it, and then retrieve it in real time to aid planning, mapping, and other orientation. Humans are perhaps unique in the extent to which these processes are abstracted and interwoven with language.
People who have investigated the phenomenon of human intelligence have long recognized that there are many dimensions to it. It is instructive that, even within our own species (which we can access through shared language, shared sensibilities and lived experiences), it is quite difficult to nail down intelligence. Much less with other species. Bears and their kin don't speak a verbal language in any sense that we recognize it, and orient to the world in fundamentally different ways; for example, with a highly developed sense of smell.
All of that said, species with comparatively big brains tend to be "more intelligent." This follows from the simple fact that a big brain provides more space and related wet wiring for carrying out complex sensory functions and cognitive tasks. And it is has been pretty conclusively shown that this is best defined in a relative sense--as unit volume of brain per unit volume of body mass or some other measure of body size. These notions were probably best articulated in a book devoted to the topic written by Stephen Gould ("The Mismeasure of Man").
That said, the part of the brain that contributes proportionately the most to brain volume matters in any reckoning of "intelligence." Perhaps most relevant is the relative volume of the frontal cortex and, of that, the neocortex. These areas of the brain are the most closely associated with spatial reasoning and conscious thought, including the deployment of abstractions.
However, we are not relegated to looking exclusively at volumes of brain structures to estimate intelligence; there are many more direct ways that involve observing animals and testing them under controlled situations to determine how fascilely they employ abstractions, how quickly they learn, and how able they are to extrapolate and otherwise deploy new knowledge.
In what follows I cover all of these indicators of intelligence, starting with total brain volume, then looking at proportional volume of different brain structures, and concluding with the results of several studies that more directly investigated the intelligence of bears. All of this is necessarily comparative--that is, in comparison to other species or taxa.
The relationships in the two figures above amplify on the basic notion that bears are relatively "big-brained." In Panel A brain volume is related to skull length; in Panel B, to body mass. Each dot represents the average for a given carnivore species, with bear species denoted by the larger brown dots, and individual bear species by four-letter acronyms. Bears stake out the extremes of large size for these relationships, which means that there aren't members of other taxa in the same size range to provide a more definitive contrast. For this reason the statistically fitted relationships are shown based on all species, including bears (gray dashed line), as well as based on non-bear species alone, with this relationship extrapolated into the size range of the bears (solid black line).
The relationship extrapolated from other species is consistent with the big-brain status of bears. Of the bears, the sun bear (Urmal, Ursus malayanus) and Asiatic black bear (Urth, U. thibetanus) have relatively the largest brains, perhaps along with the polar bear (Urmar, U. maritimus). The other bear species tend to fall along or closer to the main trend line, meaning they don't exhibit any major deviations that would indicate greater or lesser brain function (intelligence?) than one might expect by their size. One might conclude from this that bear species of the Southeast Asian lineage (Urth, Urmal, and Urur) tend to be "smarter." Another conclusion might be that the remaining bear species are not any more intelligent than size alone dictates. But, next, let's consider the relative size of different brain structures, especially those more overtly identified with intelligence.
www.allgrizzly.org/intelligence
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Post by tyrannosaurs on Jul 14, 2021 11:24:19 GMT -5
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Post by tyrannosaurs on Aug 4, 2021 7:51:36 GMT -5
Lion and tiger bone circumference: photos.app.goo.gl/WBJkqRZwhpf6GgaA9Felis bone allometry: Background Studies of bone allometry typically use simple measurements taken in a small number of locations per bone; often the midshaft diameter or joint surface area is compared to body mass or bone length. However, bones must fulfil multiple roles simultaneously with minimum cost to the animal while meeting the structural requirements imposed by behaviour and locomotion, and not exceeding its capacity for adaptation and repair. We use entire bone volumes from the forelimbs and hindlimbs of Felidae (cats) to investigate regional complexities in bone allometry. journals.plos.org/plosone/article?id=10.1371/journal.pone.0004742Interspecific scaling of the morphology and posture of the limbs during the locomotion of cats: For phylogenetically diverse mammals, ranging from small rodents to large ungulates, the generalization that limb erectness increases with increased size is supported by some size-dependent scaling relationships of appendicular skeletal anatomy as well as a limited number of direct observations of limb posture during locomotion. If size alone is the causal basis for different limb posture, then the erectness of limbs should increase significantly with increased size within a phylogenetically narrow lineage, but such data are sparse. Thus, to better establish the correlation between size and posture of mammalian limbs, we quantified the scaling relationships between mass and limb dimensions and kinematics during walking of nine species within the felid (cat) clade, which has qualitatively similar limb design. We studied the domestic cat, serval, ocelot, lynx, leopard, cheetah, cougar, lion and tiger, which had masses ranging from <4·kg to nearly 200·kg. Apart from variation associated with overall size, the lengths of the appendicular skeletal structures of most of the felid species were morphologically very similar in multivariate space. The kinematics of the limbs were also relatively uniform, and size had little predictive value for limb posture among felid species. Only three out of a total of 24 angular variables at footfall and midstance changed significantly (0.02<P<0.05) with increased mass. Thus, in contrast to previous broadly comparative studies of mammals, larger species of felids did not have more upright limbs than smaller species. Other sources: books.google.co.il/books?id=ar8EAAAAQAAJ&pg=PR50&dq=measurements+of+ulna,+felis+spelaea&redir_esc=y#v=onepage&q&f=false books.google.co.il/books?id=HdkPAAAAQAAJ&pg=PA42&dq=certain+bones+of+a+quadruped&redir_esc=y#v=onepage&q=certain%20bones%20of%20a%20quadruped&f=falsebooks.google.co.il/books?id=eXECAAAAQAAJ&pg=PA164&dq=density+of+the+bones+of+a+lion&redir_esc=y#v=onepage&q=density%20of%20the%20bones%20of%20a%20lion&f=falsebooks.google.co.il/books?id=rHbRlww0SSMC&pg=RA1-PA380&dq=density+of+the+bones+of+a+lion&redir_esc=y#v=onepage&q=density%20of%20the%20bones%20of%20a%20lion&f=falsebooks.google.co.il/books?id=4T8VAAAAYAAJ&pg=PA175&dq=we+must+attribute+this+circumstance+to+the+remarkable+hardness+of+the+bone+of+the+foreleg&redir_esc=y#v=onepage&q=we%20must%20attribute%20this%20circumstance%20to%20the%20remarkable%20hardness%20of%20the%20bone%20of%20the%20foreleg&f=falsebooks.google.co.il/books?id=_rEVAAAAYAAJ&pg=PA222&dq=the+bones+of+the+lion,+the+most+robust+of+the+genus&redir_esc=y#v=onepage&q=the%20bones%20of%20the%20lion%2C%20the%20most%20robust%20of%20the%20genus&f=false The last sources are credited to Brentlion. He send me them. Last sources: Quantifying morphological adaptations using direct measurements: The carnivoran appendicular skeleton as a case study: anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.24453It took me good time to collect these.
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Post by Gorilla king on Sept 15, 2021 17:12:26 GMT -5
MEASUREMENTS OF THE HUMERUS BETWEEN BROWN BEAR, LION, AND WOLF:
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Post by arctozilla on Oct 1, 2021 8:37:07 GMT -5
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Post by oldindigosilverback on Oct 17, 2021 6:31:24 GMT -5
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Post by arctozilla on Oct 18, 2021 12:37:05 GMT -5
Reply #17: Oh shit good stuff. Never seen that before.
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Post by tyrannosaurs on Oct 20, 2021 13:46:22 GMT -5
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Post by Gorilla king on Nov 7, 2021 19:36:01 GMT -5
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