The hominin footprint record spans ~3.6 Ma, from Late Pliocene to Holocene, and thus also spans a... more The hominin footprint record spans ~3.6 Ma, from Late Pliocene to Holocene, and thus also spans a temporal duration corresponding to many of the major events in hominin evolution. While the oldest (~3.6 Ma) tracks from Laetoli (Tanzania) have been attributed, provisionally, to genus Australopithecus, all others are attributed to various species of the genus Homo, including H. erectus (H. ergaster), H. neanderthalensis, and H. sapiens.
... greater commitment to terrestriality. The Laetoli hominin footprints 448 indicate a foot that... more ... greater commitment to terrestriality. The Laetoli hominin footprints 448 indicate a foot that possessed these modifications to the prehensile portion of the foot, but 449 21 retained the flexible midfoot. Analyses of early hominin ...
Narrow allometry is used to compare Ardipithecus ramidus molar and body segment lengths and propo... more Narrow allometry is used to compare Ardipithecus ramidus molar and body segment lengths and proportions to those of living primates, with the goal of reconstructing fossil behavior and exploring how lengths and proportions bear on phylogeny. Comparatively short hands and upper limbs suggest Ardipithecus was less adept at forelimb suspension and vertical climbing than are great apes. Its tibial and tarsal lengths, suggest bonobo-like leaping ability. Its short lower limbs, but long toes relative to humans, are not conducive to habitual bipedality. When terrestrial, Ardipithecus would have engaged in palmigrade quadrupedality. Compared to the semi-digitigrade baboon its long fingers and toes suggest a less marked terrestrial commitment and agree with carpal anatomy reflecting full palmigrady. Molar dimensions and surface areas are similar to those of baboons and drills, but greater than in chimpanzees, indicating a diet with less fruit and more roughage than that of chimpanzees. Ardipithecus dimensions reflect a generalized ape, able to move in trees and on the ground, and exploit food sources in woodlands, grasslands and/or flooded terrain. These abilities are well-suited to the mosaic habitats that characterize Africa at 11°N. Parsimonious reconstruction of the common human/African ape ancestor suggests the short upper limbs and metacarpals of Ardipithecus are too derived to belong to an exclusive human ancestor. Because parsimony is a theoretical construct and not an evolutionary reality, derived segment lengths alone do not prove conclusively Ardipithecus is not such an ancestor. Description in Ardipithecus of complex anatomy uniquely shared by humans and African apes, that leaves a record of reversals or parallelisms, would be a first step in showing whether this fossil qualifies as such an ancestor.
"Jeff Meldrum's book Sasquatch: Legend Meets SCienCe brings a much needed level of scie... more "Jeff Meldrum's book Sasquatch: Legend Meets SCienCe brings a much needed level of scientific analysis to the sasquatch—or Bigfoot—debate. Does sasquatch exist? There are countless people—especially indigenous people—in different parts of America who claim to have ...
The foot, perhaps more than any other region of the primate body reflects the interaction of posi... more The foot, perhaps more than any other region of the primate body reflects the interaction of positional behaviors with the geometric properties of available supports. The ability to reverse the hind foot during hindlimb suspension while hanging from a horizontal support or descending a large diameter vertical trunk has been noted in many arboreal mammals, including primates. Observations of Varecia variegata in the wild and under seminatural conditions document hindlimb suspension in this lemurid primate. The kinematics and skeletal correlates of this behavior are examined. Analogy is made with the form and function exhibited by nonprimate mammalian taxa employing this behavior. Examples of carnivores and rodents display very similar adaptations of the tarsals while other mammals, such as the xenarthrans, accomplish a similar end by means of different morphologies. However, a suite of features is identified that is shared by mammals capable of hind foot reversal. Hindlimb suspension effectively increases the potential feeding space available to a foraging mammal and represents a significant, and often unrecognized, alternative adaptive strategy to forelimb suspension and prehensile-tail suspension in primates.
The hominin footprint record spans ~3.6 Ma, from Late Pliocene to Holocene, and thus also spans a... more The hominin footprint record spans ~3.6 Ma, from Late Pliocene to Holocene, and thus also spans a temporal duration corresponding to many of the major events in hominin evolution. While the oldest (~3.6 Ma) tracks from Laetoli (Tanzania) have been attributed, provisionally, to genus Australopithecus, all others are attributed to various species of the genus Homo, including H. erectus (H. ergaster), H. neanderthalensis, and H. sapiens.
... greater commitment to terrestriality. The Laetoli hominin footprints 448 indicate a foot that... more ... greater commitment to terrestriality. The Laetoli hominin footprints 448 indicate a foot that possessed these modifications to the prehensile portion of the foot, but 449 21 retained the flexible midfoot. Analyses of early hominin ...
Narrow allometry is used to compare Ardipithecus ramidus molar and body segment lengths and propo... more Narrow allometry is used to compare Ardipithecus ramidus molar and body segment lengths and proportions to those of living primates, with the goal of reconstructing fossil behavior and exploring how lengths and proportions bear on phylogeny. Comparatively short hands and upper limbs suggest Ardipithecus was less adept at forelimb suspension and vertical climbing than are great apes. Its tibial and tarsal lengths, suggest bonobo-like leaping ability. Its short lower limbs, but long toes relative to humans, are not conducive to habitual bipedality. When terrestrial, Ardipithecus would have engaged in palmigrade quadrupedality. Compared to the semi-digitigrade baboon its long fingers and toes suggest a less marked terrestrial commitment and agree with carpal anatomy reflecting full palmigrady. Molar dimensions and surface areas are similar to those of baboons and drills, but greater than in chimpanzees, indicating a diet with less fruit and more roughage than that of chimpanzees. Ardipithecus dimensions reflect a generalized ape, able to move in trees and on the ground, and exploit food sources in woodlands, grasslands and/or flooded terrain. These abilities are well-suited to the mosaic habitats that characterize Africa at 11°N. Parsimonious reconstruction of the common human/African ape ancestor suggests the short upper limbs and metacarpals of Ardipithecus are too derived to belong to an exclusive human ancestor. Because parsimony is a theoretical construct and not an evolutionary reality, derived segment lengths alone do not prove conclusively Ardipithecus is not such an ancestor. Description in Ardipithecus of complex anatomy uniquely shared by humans and African apes, that leaves a record of reversals or parallelisms, would be a first step in showing whether this fossil qualifies as such an ancestor.
"Jeff Meldrum's book Sasquatch: Legend Meets SCienCe brings a much needed level of scie... more "Jeff Meldrum's book Sasquatch: Legend Meets SCienCe brings a much needed level of scientific analysis to the sasquatch—or Bigfoot—debate. Does sasquatch exist? There are countless people—especially indigenous people—in different parts of America who claim to have ...
The foot, perhaps more than any other region of the primate body reflects the interaction of posi... more The foot, perhaps more than any other region of the primate body reflects the interaction of positional behaviors with the geometric properties of available supports. The ability to reverse the hind foot during hindlimb suspension while hanging from a horizontal support or descending a large diameter vertical trunk has been noted in many arboreal mammals, including primates. Observations of Varecia variegata in the wild and under seminatural conditions document hindlimb suspension in this lemurid primate. The kinematics and skeletal correlates of this behavior are examined. Analogy is made with the form and function exhibited by nonprimate mammalian taxa employing this behavior. Examples of carnivores and rodents display very similar adaptations of the tarsals while other mammals, such as the xenarthrans, accomplish a similar end by means of different morphologies. However, a suite of features is identified that is shared by mammals capable of hind foot reversal. Hindlimb suspension effectively increases the potential feeding space available to a foraging mammal and represents a significant, and often unrecognized, alternative adaptive strategy to forelimb suspension and prehensile-tail suspension in primates.
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