It’s been awhile since we looked at anything wet.
A new robust-ribbed sauropterygian, Paludidraco ( Fig. 1, Middle Triassic) does indeed share many traits with Simosaurus, as described by Chaves et al. 2018.
A welcome confirmation!
Due to its tiny dentition, Paludidraco was originally considered a likely filter feeder, distinct from related, long-toothed nothosaurs and plesiosaurs. Simosaurus also has relatively tiny teeth, but on a larger skull and fewer in number. That’s evolution at work!
Isn’t it great to see these two related taxa together? Doesn’t it make compare and contrast so much easier? See the evolution of the human ear bones from primitive jaw bones illustration here for another great example of comparative anatomy.
Chaves et al. 2018 provided
a cladogram of marine reptile relationships (Fig. 2). Most of these taxa are also included in the large reptile tree ( LRT, 1261 taxa, subsets Figs. 3, 4), which includes many times more taxa and more marine reptiles. Missing from the Chavez team cladogram (Fig. 2) is the genus/taxon Anningsaura, which links nothosaurs to pistosaurs + plesiosaurs in the LRT. The Chaves et al. cladogram, nests Cymatosaurus (Fig. 4) and Corosaurus basal to Pistosaurus + plesiosaurs.
The Chaves et al. 2018 cladogram
(Fig. 2) excludes many pertinent taxa, so much so that important interrelationships were missed, based on the authority of the LRT (Fig. 3), which minimizes taxon exclusion due to its wider gamut of taxon inclusion. Several taxa in the Chaves et all cladogram would shift positions when tested with more taxa (arrows in Fig. 2) as the LRT shows (Fig. 3).
had to be added to the LRT (Fig. 4) to test it fairly against the Chavez team cladogram (Fig. 2). Only the skull is known (AFAIK) from three different species.
Despite the many offshoot traits
found in Anningsaura, the rest of its traits nest it firmly at the base of the pistosaurs + plesiosaurs, where Chaves et al. nests Cymatosaurus. In the LRT Cymatosaurus nests close to Paludidraco, but more on the nothosaur side than the plesiosaur side.
Chaves C de M, Ortega F and Pérez‐García A 2018. New highly pachyostotic nothosauroid interpreted as a filter-feeding Triassic marine reptile. Biology Letters. 14 (8): 20180130.
Maisch MW 2014. A well preserved skull of Cymatosaurus (Reptilia: Sauropterygia) from the uppermost Buntsandstein (Middle Triassic) of Germany. Neues Jahrbuch für Geologie und Paläontologie – Abhandlungen. 272 (2): 213–224.