摘要 :
The ability to rotate the fourth toe to accompany the first toe in opposition of the second and third toes is well known for the Osprey Pandion haliaetus, as an adaptation to have a stronger grip in catching and carry fish. The pr...
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The ability to rotate the fourth toe to accompany the first toe in opposition of the second and third toes is well known for the Osprey Pandion haliaetus, as an adaptation to have a stronger grip in catching and carry fish. The presence of a similar ability in the Grey-headed Fish Eagle Haliaeetus ichthyaetus and Lesser Fish Eagle Haliaeetus humilis, not shared with other piscivorous eagles, has largely been overlooked. Based on the growing number of photographs of these birds on the internet, the still scarce literature on their ecology and phylogeny, and personal field observation, I draw attention to this and other traits of their morphology, speculating on their origin and adaptive value.
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摘要 :
Chameleon species have recently been adopted as models for evo-devo and macroevolutionary processes. However, most anatomical and developmental studies of chameleons focus on the skeleton, and information about their soft tissues ...
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Chameleon species have recently been adopted as models for evo-devo and macroevolutionary processes. However, most anatomical and developmental studies of chameleons focus on the skeleton, and information about their soft tissues is scarce. Here, we provide a detailed morphological description based on contrast enhanced micro-CT scans and dissections of the adult phenotype of all the forelimb and hindlimb muscles of the Veiled Chameleon (Chamaeleo calyptratus) and compare these muscles with those of other chameleons and lizards. We found the appendicular muscle anatomy of chameleons to be surprisingly conservative considering the remarkable structural and functional modifications of the limb skeleton, particularly the distal limb regions. For instance, the zygodactyl autopodia of chameleons are unique among tetrapods, and the carpals and tarsals are highly modified in shape and number. However, most of the muscles usually present in the manus and pes of other lizards are present in the same configuration in chameleons. The most obvious muscular features related to the peculiar opposable autopodia of chameleons are: (1) presence of broad, V-shaped plantar and palmar aponeuroses, and absence of intermetacarpales and intermetatarsales, between the digits separated by the cleft in each autopod; (2) oblique orientation of the superficial short flexors originating from these aponeuroses, which may allow these muscles to act as powerful adductors of the super-digits; and (3) well-developed abductor digiti minimi muscles and abductor pollicis/hallucis brevis muscles, which may act as powerful abductors of the super-digits.
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