This post follows
an earlier one that found fault with Niedzwiedzki et al. (2013) and Brusatte et al. (2011), which attempted to match four-toed Lagerpeton (Fig. 2) to five-toed Prorotodactylus and Rotodactylus ichnites, claiming these tracks represented the earliest examples of dinosauromorphs in the fossil record. Beside the morphological mismatch, which they acknowledged yet based their papers on, the large reptile tree found Lagerpeton was not even a dinosaur ancestor, but nested far afield with another chanaresuchid, Tropidosuchus (Fig. 3). Here we’ll show another Lagerpeton/Tropidosuchus sister with a metatarsal 5 lacking a pedal digit 5 sealing the deal that neither Lagerpeton, nor any close sister, could have made Prorotodactylus or Rotodactylus tracks. Even a further distant sister, Chanaresuchus (Fig. 4), lacks pedal digit 5.
Above is a specimen and its reconstruction attributed to Tropidosuchus (Bonaparte 1994), but notice the difference in the pedal proportions and other proportions. The foot morphology is much closer to Lagerpeton. This specimen also has a smaller humerus than Tropidosuchus. The pelvis is distinct from both genera. Chevrons are missing from this specimen. Chevrons may be missing form this clade, which otherwise shares a relatively wide tail base according to the caudal transverse processes.
Tropidosuchus romeri (Arcucci 1990) Late Triassic was originally considered a lagosuchid like Marasuchus but here derived from a sister to BPI 2871 and Chanaresuchus. The pes of Tropidosuchus was quite similar to that of Chanaresuchus emphasizing digit 2 with a slender metatarsal 4. The tarsals did not have a calcaneal heel.
Chanaresuchus bonapartei (Romer 1971) Anisian, Early Middle Triassic is a sister to Tropidosuchus. The most robust metatarsal was mt 2 Digit 3 was the longest. Metatarsal IV was extremely gracile and digit V was absent.
So, why are professors promoting such mismatches? Why are reviewers approving such mismatches? Better matches to Prorotodactylus and Rotodactylus can be found in several untested taxa, as we saw earlier here. There must be a syndicate operating here, friends helping friends. Sometimes Science needs critics, not friends.
As always, I encourage readers to see specimens, make observations and come to your own conclusions. Test. Test. And test again.
Evidence and support in the form of nexus, pdf and jpeg files will be sent to all who request additional data.
Arcucci A 1987. Un nuevo Lagosuchidae (Thecodontia- Pseudosuchia) de la fauna de Los Chañares (edad reptil Chañarense, Triásico Medio), La Rioja, Argentina. Ameghiniana 24, 89–94.
Bonaparte JF 1994. Dinosaurios de America del Sur. Impreso en Artes Gráficas Sagitario. Buenes Aires. 174pp. ISBN: 9504368581
Brusatte SL, Niedz´wiedzki G and Butler RJ 2011. Footprints pull origin and diversification of dinosaur stem lineage deep into Early Triassic. Proceedings of the Royal Society B, 278, 1107–1113.
Niedzwiedzki G, Brusatte SL and Butler RJ 2013. Prorotodactylus and Rotodactylus tracks: an ichnological record of dinosauromorphs from the Early–Middle Triassic of Poland. Geological Society, London, Special Publications, first published April 23, 2013. doi 10.1144/SP379.12.