Morphology of the feet in polydactyl cats

Abstract

Phases of morphology which relate to the ultimate nature and meaning of homology have remained consistently baffling. For three quarters of a century it lias been considered as axiomatic that each animal species has had a long phylogenetic histor:-during which it lias progressively deviated from earlier ancestral forms; and, for a somewhat lesser period, it has been considered as almost equally axiomatic that manifest evolutionary change is merely the outward expression of ultra-microscopic changes in the germplasm.But even if both these postulates are accepted in full, there still remains a formidable array of subsidiary questions which are as yet unanswered. Some of the latter have been discussed, from rather divergent points of view, by Bateson (1894), Boyden ( '43), Hubbs ( '44), Danforth ( '25), and others. One of the most difficult of them is that of assessing the degree of phylogenetic and ontogenetic autonomy possessed by individual structural elements such, for example, as a metacarpal bone, or the tibialis anterior muscle.Polydactylv in the cat provides excellent material for the study of some of these morphological problems. The condition is one of 110 great rarity and parallels, at least superficially, similar manifestations in man and several other species. Descriptions of feet from individual polydactyl cats have been published bJ-several authors, notably Wilder (1868), Howe

Distinctive osteology of distal flipper bones of tropical bottlenose whales, Indopacetus pacificus, from Taiwan: Mother and calf, calf with polydactyly

“…In the beluga ( Delphinapterus leucas ) there is variable duplication of the first digit (Kükenthal 1889–1893) or of the fourth or fifth digits (Kunze 1912, Yablokov 1974); and in each case there is chondro‐osseous connection with the more proximal elements of the digital ray or metacarpal. This skeletal connection between the polydactylous digit and the normal skeleton is seen in all previous odontocete cases of polydactyly, and is consistent with findings in cats (Danforth 1947; study of four litters of alcian blue/alizarin red‐stained and cleared polydactylous cat fetuses by AW) and in other domestic mammals and human beings ( e.g ., Prentiss 1903). The lack of bony or cartilaginous connection between the polydactylous digit and a normal adjacent digit, as seen in this present case in Indopacetus , contrasts with the majority of mammalian individuals with polydactyly.…”

Radial polydactyly: putting together evolution, development and clinical anatomy

“…A detailed analysis, taking into account not only the number of digits, the number of phalanges of each digit and the level of skeletal bifurcation but also including the size and shape of bones, the connections and angles between them, and their topological position relative to muscles, may allow one to discern consistent patterns within what could at first sight seem a 'chaotic' scenario. This is supported by Danforth (1947) who…”

Functional morphology and identity of the thenar pad in the subterranean genus Ctenomys (Rodentia, Caviomorpha)

“…Diogo et al (2015) proposed the topology model to account for the link between muscles and skeleton: identity and attachment of the limb tendons/muscles is settled by topological position of digits on which they insert, regardless of the anlage or developmental identity of digits. The distal insertion of tendons such as the abductor pollicis longus suggests that the first digit and the TP are so closely related that tendons interpret the information as if there were a single digit (Danforth, 1947;Crowley et al 2018), in line with Diogo et al (2015) proposal. The relation of this skeletal structure (the radial sesamoid) with the anatomical digit I elements could have driven its transformation in a digitlike structure.…”