Making a parrot's zygodactyl foot

JULIETA CARRIL , CLAUDIO G. BARBEITO , CLAUDIA P. TAMBUSSI

CABA

Simposio; LASDB2019 Simposio Latinoamericano de Biología de Desarrollo 2019; 2019

Latinoamerican Society Development Biology

The tarsometatarsus (TMT) is the result of the fusion of metatarsals II, III and IVwith the distal tarsals, and represents an innovation in the lineage of birds. Inaddition , there are different types of digits orientation in hindlimbs, beingzygodactyly (toes II and III forward oriented and toes I and IV backward oriented)clearly linked to manipulation and locomotor skills in parrots. By using a doublestain technique of ca rtilages and bones, new insights on the skeletogenesis of theTMT of the altricial monk parakeet (Myiopsitta monachus, Psittaciformes) throughthe ontogenetic trajectory and the acquisition of zygodactyly are given here,providing valuable information in t he context of comparative morphology anddevelopmental studies. Results showed: cartilaginous metatarsals at embryonicstage (S) 29; development of the trochlea of metatarsal IV at S31; metatarsals withossification centers in their mid diaphysis and devel opment of plantarly orientatedtrochlea accesoria in the trochlea of metatarsal IV (linked to zygodactyly) at S34;cartilaginous distal tarsal fused with metatarsals at S35; development of trochleasof metatarsals II and III at S36; ossification areas exte nded along diaphysis atS40+; metatarsals II and III fused at day 0.5 after hatchling (AH); metatarsal IVfused with metatarsals II+III at day 4.5 AH; TMT completely ossified with vascularforamina and hypotarsus with a single canal at day 22 AH; an skelet ogenesisdelayed compared to precocial birds.