Month: September 2022

COMPETITIVE ADVANTAGE. "There is little doubt that one of the major evolutionary assets of therian mammals was a complex foot architecture with subtly integrated articular complexes at the ankle, subtalar and traverse tarsal joints." A brilliant three part anatomical analysis of the foot across species (OJ Lewis, St Bartholemew's Hospital, London). (Therian = marsupials and placentals). https://lnkd.in/er98r8i View in LinkedIn

TALUS UPON THE CALCANEUS. "Schaeffer (1941) rightly stressed that the therapsid foot was converted into a mammalian one by superposition of the talus upon the calcaneus, correlated with a loss of weight-bearing contact between fibula and calcaneus; but little is known about how the complex articular surfaces and ligamentous apparatus of the mammalian foot came into being." https://lnkd.in/er98r8i View in LinkedIn

TARSAL RANKING. "Recent studies, and the present paper indicate that evolving foot form is replete with apomorphic characters, and moreover, that these can be keyed to reasonable functional and adaptive roles. Gregory (1910) perceptively recognized the potential importance of characters of the feet, particularly tarsals, even ranking them above teeth!" (Apomorphic = unique species trait). https://lnkd.in/er98r8i View in LinkedIn

PASSING THROUGH. "It seems quite clear that the anatomy of living marsupials (metatherians) gives a good indication of the structure of those advanced early Cretaceous therians from which the first placentals (eutherians) evolved. One might say, as has Lillegraven (1974) that the eutherians passed through a metatherian grade." https://lnkd.in/et2pUax View in LinkedIn

TALUS & CALCANEUS. "A key event in transforming the therapsid foot into a mammalian one was the superimposition of the talus upon the calcaneus. This introduced a new flexibility into the foot by providing for inversion and eversion at the subtalar joint complex." https://lnkd.in/et2pUax View in LinkedIn

DERIVATION. "The human ankle bears the clear imprint of derivation from arboreal primates which in turn were doubtless derived from very early unspecialized eutherians." https://lnkd.in/et2pUax View in LinkedIn

EUTHERIANS. "The first placentals had clearly sacrificed the talocrurals supinatory capability, facilitated by the marsupial meniscus, in favour of re-fashioning the lower extremities of tibia and rubia into a stable mortise for articulation with the re-fashioned talar body." https://lnkd.in/et2pUax View in LinkedIn

GRAFTED ON. "The chimpanzee shows certain derived features which are with little doubt grafted onto the morphology typical of the higher primates." https://lnkd.in/eSbfe-f View in LinkedIn

SUBTLE BUT DRASTIC. "The subtalar joint complex of man is quite clearly derived from the basic primate pattern, and in particular its unique structural attributes seem to have resulted from the accentuation of trends already incipient in Pan and Gorilla. Quite subtle and easily overlooked morphological changes have drastically modified the function." https://lnkd.in/eSbfe-f View in LinkedIn

FIGURE 12-14 show a lovely sequential evolution of tarsus foot bones. Beautiful depiction of a gnarly and complex structure as they were adapted for the human foot from pre-existing species. https://lnkd.in/eSbfe-f View in LinkedIn