Cranio-dental ontogeny of the pacarana Dinomys branickii Peters 1873 (Rodentia, Hystricognathi, Caviomorpha, Dinomyidae)

NORMA NASIF; FERNANDO ABDALA

JOURNAL OF MAMMALOGY

ALLIANCE COMMUNICATIONS GROUP DIVISION ALLEN PRESS

Lugar: Lawrence; Año: 2015 vol. 96 p. 1224 - 1244

0022-2372

We investigate thecranial, mandibular and dental ontogeny of the pacarana Dinomys branickii, the only extant species of the rodent Family Dinomyidae.An allometric study, including 27 variables, 21 from the skull and 6 from thelower jaw, indicates fast growth in the rostrum and palatal length butisometric growth in nasal width, rostral height, and length of the upperdiastema. Positive allometry is also present in mandibular length, in retromolar length of the lower jaw and,especially, in height of the articular process. Negative allometry is found inthe length and width of the tympanic bulla, braincase width, width of the occipitalcondyles and occipital height. We document for the first time the presence of athird premolar (dP3), represented by a tiny, rooted element, and which is lostin early postnatal ontogeny. Replacementof dP4/dp4 occurs after eruption of M3/m3. The complete eruption of P4/p4happens when M3/m3 are fully functional. Ontogenetic changes in the postnatalontogeny of the skull of D. branickii are mostly related to the developmentof the occlusal system and action of associated muscles. This is evidenced by rapidgrowth of the facial region, a deepening and strengthening of the temporal andoccipital regions and a widening of the posterior portion of the palate whichis related to the eruption and replacement of molariform teeth.  Some observed cranio-mandibular trends in theontogeny of D. branickii arereflected in the size of Ctenohystrica taxa, with small species of this lineageshowing features similar to those of juveniles of D. branickii and large species resembling adults