GYMNOPHIONA (CAECILIANS)

Benton, MJ, Donoghue, PCJ, Vinther, J, Asher, RJ, Friedman, M & Near, TJ, 2015, Constraints on the timescale of animal evolutionary history, Palaeontologia Electronica (Florence, Italy) 15 (1), pp. 1-107 : 50

CROWN GYMNOPHIONA (CAECILIANS) (46)

Node Calibrated. Divergence between Rhinetrematidae and Caeciliidae .

Fossil Taxon and Specimen. Apodops pricei Estes and Wake, 1972 , based on a single trunk vertebra from the Late Paleocene of São José de Itaboraí , Rio de Janeiro, Brazil (Divisão de Geologia e Mineralogia, Depto. Nacional de Producão Mineral, Rio de Janeiro, Brazil, DGM 551 ).

Phylogenetic Justification. Apodops pricei was identified as a caecilian related to the Holocene genus Dermophis and the extant Geotryptes. It is assigned to crown Gymnophiona based on the apomorphies of having compact vertebrae, and enlarged, projecting parapophyses ( Estes and Wake, 1972).

Minimum Age. 56 Ma

Soft Maximum Age. 145.8 Ma

Age Justification. The fissure fillings of São José de Itaboraí, near Rio de Janeiro, are dated as early Late Paleocene (Mayr et al., 2011), and the maximum age bound is then 56.0 Ma ± 0.0 Myr = 56.0 Ma ( Gradstein et al., 2012, pp. 883, 904).

Discussion. The two oldest caecilians, the Early Jurassic Eocaecilia micropodia and the Early Cretaceous Rubricacaecilia monbaroni , belong to the stem (Marjanovic and Laurin, 2007), and so are not helpful in dating. Two unnamed possible crown caecilians are an unnamed form from the Wadi Milk Formation of Sudan (Cenomanian) and a terminal Cretaceous fossil from the Pajcha Pata in Bolivia. These provide hints that older caecilians, whose fossils appear to be so immensely rare, might be found down to the base of the Cretaceous at least, dated as 145.0 Ma ± 0.8 Myr ( Gradstein et al., 2012, p. 838), so 145.8 Ma.