Tiny Coletta (Fig. 1, Modesto et al. 2002) is an important little reptile. According to the large reptile tree, Coletta is the first in the phylogenetic lineage of lepidosaur “diapsids” to have a lateral temporal fenestra (= ltf) — at least one that is homologous to the modern lizard ltf.
According to Modesto et al. (2002)
Coletta is a procolophonid from the Early Triassic nesting between Owenetta and Contritosaurus (Fig. 2) with Procolophon and Hypsognathus as more derived taxa. This assumption has proven to be invalid when applied to the larger gamut of taxa in the large reptile tree.
The large reptile tree
nested Procolophon and Hyposognathus with Diadectes and thus Coletta and Owenetta were only very distantly related to Procolophon (at least 10 nodes of intervening taxa). Instead the large reptile tree nested Coletta between Owenetta and Emeroleter (Contritosaurus has not been tested). Thus the Modesto et al. 2002 tree appears to be upside down with basal taxa at derived nodes. Modesto et al. 2002 did not include Diadectes or any lepidosaurs or any of the intervening taxa recovered in the large reptile tree. Thus taxon exclusion in an apparently too small phylogenetic analysis resulted in a tree that cannot be duplicated in a larger study.
Other ltfs have come and gone.
The ltf in Lanthanosuchus, for instance, is not homologous with those of lizards. The ltfs in synapsids, archosaurs and millerettids (including caseasaurs) are also not homologous, according to the large reptile tree.
Incomplete from the start
The ltf in lepidosaurs is primitively incomplete in that there is no jugal-quadratojugal bar and the fenestra does not form in a typical fashion, between three surrounding bones. Later taxa with a complete lower temporal fenestra bar, like Sphenodon, arrive at that secondarily.
Not derived from Youngina
The traditional paradigm holds that both archosaurs and lepidosaurs find a common ancestor close to Youngina. The large reptile tree found Youngina to be ancestral only to archosaurs and their kin, not to lepidosaurs, which nest in the other major branch of the Reptilia (= Amniota). The actual last common ancestor of lepidosaurs and archosaurs is Cephalerpeton, at the very base of the Reptilia.
Clearing up these common misconceptions in palaeontology is the major role for the large reptile tree found here. Owenettids, like Coletta, need to be removed from all procolophonid studies. And vice-versa. These distinct reptile clades are not closely related.
Chudinov PK and Vjushkov BP 1956. New Data on Small Cotylosaurs from the Permian and Triassic of the USSR. Doklady Akademii Nauk SSSR 108 (3): 547–550 [In Russian].
Modesto SP, Damiana RJ and Sues H-D 2002. A reappraisal of Coletta seca, a basal procolophonid reptile from the lower Triassic of South Africa. Palaentology 45(5):883-895.