POLYDACTYLY AND OTHER FEATURES OF THE MANUS OF THE VAQUITA, PHOCOENA SINUS

Ortega‐Ortiz, Joel G.; Villa‐Ramírez, Bernardo; Gersenowies, Jorge R.

doi:10.1111/j.1748-7692.2000.tb00924.x

Cited by 19 publications

(22 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Finally, the cuneiform is the last carpal to ossify (Figure 2a), and it may be absent in some adults (Dawson, 2003). Contrary to this pattern of carpal ossification, radiographs of the vaquita carpus (Ortega-Ortiz et al, 2000) showed that ossification proceeded in a caudal-to-cranial direction with the cuneiform and lunate beginning ossification before the scaphoid (Figure 3).…”

Section: The Unique Carpus Of the Vaquitamentioning

confidence: 95%

“…Possibly as a result of the population's genetic homogeneity, a small extra digit (with up to four phalanges) is expressed as a fixed trait in the population (Ortega-Ortiz, 1993, 2000Villa-Ramírez et al, 1996). This additional digit is enveloped in dense connective tissue and probably does not affect digit function; however, no functional studies have addressed its potential hydrodynamic effects.…”

Section: Vaquita (Phocoena Sinus)mentioning

confidence: 99%

See 1 more Smart Citation

Paedomorphic Ossification in Porpoises with an Emphasis on the Vaquita (Phocoena sinus)

Mellor¹,

Cooper²,

Torre³

et al. 2009

aquatic mammals

View full text Add to dashboard Cite

Heterochrony, the change in timing of developmental processes, is thought to be a key process shaping the numerous limb morphologies of tetrapods. Through a delayed offset in digit development, all cetaceans (i.e., whales, dolphins, and porpoises) have evolved supernumary phalanges (hyperphalangy). Moreover, some toothed cetaceans further alter digital morphologies by delayed endochondral and perichondral ossification of individual elements. In the harbor porpoise (Phocoena phocoena), these paedomorphic patterns have created poorly ossified phalangeal elements. However, no studies have addressed this morphology in other porpoise taxa. This study documents the timing of carpal and digital epiphyseal ossification in the poorly studied vaquita (Phocoena sinus) based on radiographs (n = 18) of known-age specimens. Patterns of vaquita manus ossification were compared between other porpoise and delphinid taxa. Adult vaquitas are paedomorphic in carpal, metacarpal, and digital development as they maintain a juvenile ossification pattern relative to that of other porpoise species of equivalent ages. Vaquitas also ossify fewer carpal elements as compared to other porpoise and some delphinid cetaceans, and ossification arrests relative to that of the harbor porpoise. Vaquitas also display sexual dimorphism as females reach a greater body size and display more ossified elements in the manus relative to their paedomorphic male cohorts.

show abstract

Section: The Unique Carpus Of the Vaquitamentioning

confidence: 95%

Section: Vaquita (Phocoena Sinus)mentioning

confidence: 99%

Paedomorphic Ossification in Porpoises with an Emphasis on the Vaquita (Phocoena sinus)

Mellor¹,

Cooper²,

Torre³

et al. 2009

aquatic mammals

View full text Add to dashboard Cite

show abstract

“…In their description of polydactyly in Phocoena sinus, Ortega-Ortiz et al (2000) do not discuss deltashaped bones. However, based on their illustrations delta-shaped bones are present in this species, with similar distribution as in P. phocoena.…”

Section: Modifications Of Perichondral Ossificationmentioning

confidence: 97%

Patterns of ossification in the manus of the harbor porpoise (Phocoena phocoena): Hyperphalangy and delta‐shaped bones

Dawson

2003

Journal of Morphology

View full text Add to dashboard Cite

With the transition from terrestrial to aquatic habitats, cetacean forelimbs have undergone significant modifications in bone morphology and soft tissue distribution. Some, but not all, of these modifications are also demonstrated in other lineages of extant and extinct secondarily aquatic tetrapods. This study examines the ontogenetic pattern of ossification of the manus of the harbor porpoise (Phocoena phocoena), using plain film radiography. Two modifications examined are hyperphalangy (number of phalanges per digit increased beyond the typical mammalian number) and the morphology of delta-shaped bones. Hyperphalangy in Phocoena phocoena is apparent in digits 2 and 3. Phalangeal counts in all digits are variable (sometimes between the right and left flippers of the same individual) and are not necessarily correlated with age. Phalangeal ossification and epiphyseal fusion proceeds along the proximo-distal axis within each digit. In addition, digits 2 and 3 are at a more advanced stage of ossification than more abaxial digits. Delta-shaped bones appear to be a normal stage in the ossification of phalanges in all digits except the third, and may persist in the adult in certain digits. In humans, this morphology is a developmental anomaly usually associated with other malformations, such as polydactyly or syndactyly. Delta-shaped bones in the cetacean manus display a consistent orientation and the process by which they are formed may be similar to that in extinct marine reptiles.

show abstract

“…The cetacean manus has been the focus of numerous descriptive studies documenting the patterns of digit ossification and phalangeal counts in isolated taxa (e.g., Gihr et al, 1982;Benke, 1993;Watson et al, 1994;Calzada and Aguilar, 1996;Ortega-Ortiz and Villa-Ramirez, 2000;Richardson and Oelschlä ger, 2002;Dawson, 2003;Fedak and Hall, 2004), but only recently has a more synthetic view of digital evolution emerged. Using a limited number of taxa, Fedak and Hall (2004) hypothesized that the derived condition of hyperphalangy (unconventionally defined as exhibiting a phalangeal formula greater than 4/6/6/6/6 which is greater than the earliest known tetrapods and, therefore, represents a new tetrapod morphology) evolved three separate times within cetaceans.…”

mentioning

confidence: 99%

Evolution of hyperphalangy and digit reduction in the cetacean manus

Cooper

Berta

Dawson

et al. 2007

The Anatomical Record

View full text Add to dashboard Cite

Cetaceans (whales, dolphins, and porpoises) have a soft tissue flipper that encases most of the forelimb, and elongated digits with an increased number of phalanges (hyperphalangy). In addition, some cetaceans exhibit a reduction in digit number. Although toothed cetaceans (odontocetes) are pentadactylous, most baleen whales (mysticetes) are tetradactylous and also lack a metacarpal. This study conducts a survey of cetacean metacarpal and phalangeal morphologies, traces the evolution of hyperphalangy in a phylogenetic context, optimizes characters onto previously published cetacean phylogenies, and tests various digit loss hypotheses. Dissections were performed on 16 cetacean flippers representing 10 species (8 mysticetes, 2 odontocetes). Phalangeal count data were derived from forelimb radiographs (36 odontocetes, 5 mysticetes), osteological specimens of articulated forelimbs (8 mysticetes), and were supplemented with published counts. Modal phalangeal counts were coded as ordered and unpolarized characters and optimized onto two known cetacean phylogenies. Results indicate that digital ray I is reduced in many cetaceans (except Globicephala) and all elements of digital ray I were lost in tetradactylous mysticetes. Fossil evidence indicates this ray may have been lost approximately 14 Ma. Most odontocetes also reduce the number of phalangeal elements in digit V, while mysticetes typically retain the plesiomorphic condition of three phalanges. Results from modal phalangeal counts show the greatest degree of hyperphalangy in digits II and III in odontocetes and digits III and IV in mysticetes. Fossil evidence indicates cetacean hyperphalangy evolved by at least 7-8 Ma. Digit loss and digit positioning may underlie disparate flipper shapes, with narrow, elongate flippers facilitating fast swimming and broad flippers aiding slow turns. Hyperphalangy may help distribute leading edge forces, and multiple interphalangeal joints may smooth leading edge flipper contour. Anat Rec, 290:654-672, 2007. 2007 Wiley-Liss, Inc.

show abstract

POLYDACTYLY AND OTHER FEATURES OF THE MANUS OF THE VAQUITA, PHOCOENA SINUS

Cited by 19 publications

References 20 publications

Paedomorphic Ossification in Porpoises with an Emphasis on the Vaquita (<I>Phocoena sinus</I>)

Paedomorphic Ossification in Porpoises with an Emphasis on the Vaquita (<I>Phocoena sinus</I>)

Patterns of ossification in the manus of the harbor porpoise (Phocoena phocoena): Hyperphalangy and delta‐shaped bones

Evolution of hyperphalangy and digit reduction in the cetacean manus

Contact Info

Product

Resources

About