Fred Ruhe
Well-known member
N. Adam Smith & Julia A. Clarke, 2014
Osteological Histology of the Pan-Alcidae (Aves, Charadriiformes): Correlates of Wing-Propelled Diving and Flightlessness
The Anatomical Record 297: 188-199
Pdf at http://people.duke.edu/~ns137/Smith&Clarke2014.pdf
Abstract:
Although studies of osteological morphology, gross myology, myological
histology, neuroanatomy, and wing-scaling have all documented anatomical
modifications associated with wing-propelled diving, the osteohistological
study of this highly derived method of locomotion has been limited to penguins.
Herein we present the first osteohistological study of the derived forelimbs
and hind limbs of wing-propelled diving Pan-Alcidae (Aves, Charadriiformes). In addition to detailing differences between wing-propelled diving charadriiforms and nondiving charadriiforms, microstructural modifications to the humeri, ulnae and femora of extinct flightless pan-alcids are contrasted with those of volant alcids. Histological thin-sections of four species of pan-alcids (Alca torda, †Alca grandis, †Pinguinus impennis, †Mancalla cedrosensis) and one outgroup charadriiform (Stercorarius longicaudus) were compared. The forelimb bones of wing-propelled diving charadriiforms were found to have significantly thicker (22%) cortical bone walls. Additionally, as in penguins, the forelimbs of flightless pan-alcids are found to be osteosclerotic.
However, unlike the pattern documented in penguins that display thickened
cortices in both forelimbs and hind limbs, the forelimb and hind limb elements of pan-alcids display contrasting microstructural morphologies with
thickened forelimb cortices and relatively thinner femoral cortices. Additionally, the identification of medullary bone in the sampled †Pinguinus impennis specimen suggests that further osteohistological investigation could provide an answer to longstanding questions regarding sexual dimorphism of Great Auks.
Finally, these results suggest that it is possible to discern volant from flightless wing-propelled divers from fragmentary fossil remains.
Fred Ruhe
Osteological Histology of the Pan-Alcidae (Aves, Charadriiformes): Correlates of Wing-Propelled Diving and Flightlessness
The Anatomical Record 297: 188-199
Pdf at http://people.duke.edu/~ns137/Smith&Clarke2014.pdf
Abstract:
Although studies of osteological morphology, gross myology, myological
histology, neuroanatomy, and wing-scaling have all documented anatomical
modifications associated with wing-propelled diving, the osteohistological
study of this highly derived method of locomotion has been limited to penguins.
Herein we present the first osteohistological study of the derived forelimbs
and hind limbs of wing-propelled diving Pan-Alcidae (Aves, Charadriiformes). In addition to detailing differences between wing-propelled diving charadriiforms and nondiving charadriiforms, microstructural modifications to the humeri, ulnae and femora of extinct flightless pan-alcids are contrasted with those of volant alcids. Histological thin-sections of four species of pan-alcids (Alca torda, †Alca grandis, †Pinguinus impennis, †Mancalla cedrosensis) and one outgroup charadriiform (Stercorarius longicaudus) were compared. The forelimb bones of wing-propelled diving charadriiforms were found to have significantly thicker (22%) cortical bone walls. Additionally, as in penguins, the forelimbs of flightless pan-alcids are found to be osteosclerotic.
However, unlike the pattern documented in penguins that display thickened
cortices in both forelimbs and hind limbs, the forelimb and hind limb elements of pan-alcids display contrasting microstructural morphologies with
thickened forelimb cortices and relatively thinner femoral cortices. Additionally, the identification of medullary bone in the sampled †Pinguinus impennis specimen suggests that further osteohistological investigation could provide an answer to longstanding questions regarding sexual dimorphism of Great Auks.
Finally, these results suggest that it is possible to discern volant from flightless wing-propelled divers from fragmentary fossil remains.
Fred Ruhe
