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Apr 28, 2020 12:10:13 GMT -5
tom likes this
Post by brobear on Apr 28, 2020 12:10:13 GMT -5
The Size Range of Amphicyonidae
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Apr 28, 2020 12:15:47 GMT -5
Post by brobear on Apr 28, 2020 12:15:47 GMT -5
en.wikipedia.org/wiki/Bear_dog Amphicyonids ranged in size from as small as 5 kg (11 lb) and as large as 100 to 773 kg (220 to 1,704 lb) and evolved from wolf-like to bear-like body forms. Early amphicyonids, such as Daphoenodon, possessed a digitigrade posture and locomotion (walking on their toes), while many of the later and larger species were plantigrade or semiplantigrade. The amphicyonids were obligate carnivores, unlike the Canidae, which are hypercarnivores or mesocarnivores.
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Deleted
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Aug 18, 2022 18:05:55 GMT -5
Post by Deleted on Aug 18, 2022 18:05:55 GMT -5
There are 2 scientifc papers available online about the body size of amphicyonids:
- Body mass estimation in amphicyonid carnivoran mammals: A multiple regression approach from the skull and skeleton. And yes, some of them were apparently very big, bigger than the largest extinct cats. Amphicyon ingens was stated to have reached 547kg, that's larger than a normal polar bear. We have a mandibule which suggest an individual weighting 773kg for another species but i think we must be cautious, i don't know if a mandibule is a good indicator.
- The anatomical characteristics of a giant miocene amphicyonid humerus from Pakistan. The paper indicates an animal between 358kg and 534kg. There are some measurements about the distal humeral maximum width but we should compare with more data.
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Aug 18, 2022 23:43:54 GMT -5
Post by brobear on Aug 18, 2022 23:43:54 GMT -5
There are 2 scientifc papers available online about the body size of amphicyonids: - Body mass estimation in amphicyonid carnivoran mammals: A multiple regression approach from the skull and skeleton. And yes, some of them were apparently very big, bigger than the largest extinct cats. Amphicyon ingens was stated to have reached 547kg, that's larger than a normal polar bear. We have a mandibule which suggest an individual weighting more 773kg for another species but i think we must be cautious, i don't know if a mandibule is a good indicator. - The anatomical characteristics of a giant miocene amphicyonid humerus from Pakistan. The paper indicates an animal between 358kg and 534kg. There are some measurements about the distal humeral maximum width but we should compare with more data. This is an interesting post. You should also include the sources of your data.
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Aug 19, 2022 4:36:26 GMT -5
Post by Deleted on Aug 19, 2022 4:36:26 GMT -5
I have included my sources by citing the publications. You can download them.
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Aug 19, 2022 5:06:12 GMT -5
Post by brobear on Aug 19, 2022 5:06:12 GMT -5
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Aug 19, 2022 5:09:59 GMT -5
Post by brobear on Aug 19, 2022 5:09:59 GMT -5
Conclusions: As revealed by principal components analysis, based on the linear dimensions employed in this study, the craniodental morphology of beardogs appears to be “intermediate” between the morphologies of the living canids and ursids. Amphicyonids displayed very different skull proportions from living felids and hyaenids, the two feliform families included in this analysis. Whereas some morphologic convergences be− tween the extinct amphicyonids and living felids and hyaenids have been reported (Bergounioux and Crouzel 1973; Viranta 1996; Hunt 1998; Sorkin 2006), the results of this study sug− gest that living canids and ursids, which were employed here, are the best available comparators. The principal goal of our study was the estimation of the body masses of amphicyonids, particularly those belonging to the Daphoeninae and Amphicyoninae. Therefore, given the well−recognized morphological resemblances between the liv− ing caniforms and amphicyonids, we have used the extant spe− cies of Canidae and Ursidae for adjusting regression functions that allow estimation of amphicyonid body mass. In addition, we have also estimated their mass values with the equations published by Van Valkenburgh (1990) and Anyonge (1993), adjusted using all large−bodied extant carnivoran families, in order to check the biases in our estimates. In fact, the estimates calculated from these functions fall within the range of mass estimates obtained in this study for each species. As a general rule, multiple regressions tend to predict body mass more accurately than single ones, although the best mass predictor is the one derived from femoral dimen− sions, an equation which incorporates only one variable, the mediolateral diameter of the femur at midshaft. As expected, the regression equations derived from the distal limb seg− ments are worse predictors of body mass than those adjusted with the proximal ones. This may suggest that the dimen− sions of the distal limb segments are more correlated with the carnivoran locomotor adaptations and/or hunting techniques (Anyonge 1993, 1996). However, it may also reflect the fact that the distal limb segments are composed of two bones that jointly bear the weight of the animal, while the proximal seg− ments are made up of only a single bone (Meachen−Samuels and Van Valkenburgh 2009). The craniodental equations are worse mass predictors than those adjusted with the major limb bones. Also, body mass estimates derived for amphicyonids from skull mea− surements should be taken with caution, not only because these functions have lower predictive power than those ad− justed with the postcranial skeleton, but also because amphi− cyonids have disproportionately large heads in relation to body mass (Finarelli 2006). For this reason, although we present here the mass values of amphicyonids derived from the craniodental skeleton, these values merit some skepti− cism, particularly for the larger species. A set of multiple regression functions was applied to amphicyonids according to the availability of measurements. The values of body mass estimated for beardogs seem to show a relationship between the increase in body size and the ap− pearance of different ecomorphs during the evolution of this carnivoran family. Specifically, the species of amphicyonids cluster in three size groups: (i) the small daphoenines, which converge on the living foxes, jackals and coyote; (ii) the mid−sized daphoenines, whose anatomy resembles in some as− pects that of pack−hunting canids (e.g., Canis lupus or Lycaon pictus); and (iii) the largest amphicyonines, which most proba− bly should be envisaged as bear−like foragers. This study suggests that body size increased in amphi− cyonids through their evolutionary history, which agrees with previous studies (Hunt 1998; Finarelli and Flynn 2006, 2007), and that the appearance of new ecomorphs in the family (e.g., canid−like or bear−like) is probably expressed as a progressive alteration in skeletal form and body size (i.e., allometry) as in− fluenced by natural selection. Future studies on the relation− ship among size and shape in amphicyonids are crucial for un− derstanding the morphological evolution of beardogs.
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Aug 19, 2022 5:13:54 GMT -5
Post by OldGreenGrolar on Aug 19, 2022 5:13:54 GMT -5
So we have a giant Amphicyon which is similar in size to a polar bear.
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Aug 19, 2022 5:30:49 GMT -5
Post by Deleted on Aug 19, 2022 5:30:49 GMT -5
Difficult to say. I have no humeral or femoral measurement . But i think it is safe to claim that they were (for the largest species) bigger than the extant felids and probably as large as the largest prehistoric cats if not a bit larger.
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