Trioceros jacksonii (Boulenger 1896) is a living agamid and a sister to Phyrnosoma within the clade Iguania. This lizard has a three-horned face and a Triceratops-like shield. The tongue is hyper-extensible for catching insects on tree branches and leaves. Fingers 1-3 oppose fingers 4 and 5. Toes 1 and 2 oppose toes 3-5. The curled tail is prehensile. Jackson's chameleon gives birth to live offspring. Eight to thirty are born after a six-month gestation. Sexual maturity is at 5 months of age. Adult size is 12 in. (30cm).

The manus and pes of a chameleon (Diaz and Trainor 2015) are shown below. Second picture relabels fingers.

Unnamed stem chameleon (Daza et al. 2016; Early Cretaceous, 1.2cm in length; JZC Bu154) is a neonate stem chameleon preserved in amber. It also nests basal to horned lizards like Phrynosoma. Note the long, straight hyoid forming the base of the shooting tongue. The split fingers and toes of extant chameleons had not yet developed in this taxon.

Boulenger GA 1896 Description of a new chameleon from Uganda. Annual Natural History 6(17):376.

Daza JD et al. 2016. Mid-Cretaceous amber fossils illuminate the past diversity of tropical lizards. Sci. Adv. 2016; 2 : e1501080 4 March 2016

Diaz RE Jr. and Trainor PA 2015. BMC Evolutionary Biology201513:184.

wiki/Trioceros