There are those
who practice taxon exclusion in their search for taxon ancestors. Now, Paparella et al. 2018 can be counted among them as they bring us a wonderful new find, Primitivus manduriensis from the Late Cretaceous of Italy. They correctly nest it as a pre-snake and a dolichosaur (Fig. 1). Primitivus also preserves snake-like scales.
Unfortunately, due to taxon exclusion
the Paparella team nest Primitivus with the invalid clade ‘Pythonomorpha‘ (mosasaurs + snakes) rather than the more broadly tested pre-dolichosaurs (= ardeosaurs): Ardeosaurus, Eichstättisaurus and tiny Jucaraseps, none of which are mentioned in the text. These taxa are ancestral to the dolichosaurs leading to snakes in the large reptile tree (LRT, 1236 taxa, Fig. 2). The LRT tests all these candidates and finds mosasaurs and varanids nest elsewhere, apart from snakes, dolichosaurs, ardeosaurs and geckos. Deletion of the ardeosaurs makes no change in the LRT tree topology. This is a strong nesting.
The Paparella team also nest tiny Tetrapodophis
at the stem of Mosasauroidea + Dolichosauridae and apart from snakes (Fig. 1), rather than basal to snakes, as in the LRT (Fig. 2).
an otherwise excellent paper has this fatal flaw due to taxon exclusion. Sometimes I wonder why workers don’t test taxa that years ago were found relevant in the LRT. That’s why the LRT is online, available 24/7 worldwide.
As we learned earlier,
phylogenetic miniaturization gave us both aquatic dolichosaurs (via tiny Jucaraseps) and later, terrestrial snakes (via tiny Tetrapodophis).
There is very little difference, apart from size,
between the larger Pontosaurus and the smaller Primitivus. Not sure why the Paparella team did not present skull identification in their primary publication.
Paparella I, Palci A, Nicosia U and Caldwell MW 2018. A new fossil marine lizard with soft tissues from the Late Cretaceous of southern Italy. Royal Society Open Science 5: 172411. http://dx.doi.org/10.1098/rsos.172411
Publicity including in vivo restorations: