Non-dinosaurian Dinosauromorpha (Langer et al. 2013)

Continuing to push Lagerpeton as a “dinosauromorph” (which is traditional thinking), Langer et al. (2013) continues to ignore certain basic facts starting in the feet that divide pararchosauriforms (including Lagerpeton) and euarchosauriforms (including dinosaurs) into two major clades.

The feet of Euarchosauriformes (above in white) and Pararchosauriformes (below in grey). No higher euarchosauriformes have a longer digit 4 than 3. Both sets of feet share more traits with each other, which removes Lagerpeton from the lineage of dinosaurs, but puts it in the line of descent from Diandongosuchus.

Figure 1. Click to enlarge. The feet of Euarchosauriformes (above in white) and Pararchosauriformes (below in grey). No higher euarchosauriformes have a longer digit 4 than 3. Both clades share more foot traits with each other, which removes Lagerpeton from the lineage of dinosaurs in the Euarchosauriformes, and puts it in the line of descent from Diandongosuchus (with its long digit 4) and/or Proterochampsa (with its short digit 1). Also note that the ascending process of the astragalus is posterior in Lagerpeton, anterior in dinosaurs.

Euarchosauriformes
It’s unfortunate that so few euarchosauriform feet are known that include a complete digit 4, but what we do know demonstrates that digit 4 is always shorter than 3 and metatarsal 4 is always shorter than mt3.

Pararchosauriformes
In this clade pedal digit 4 can sometimes be longer than 3 and metarsal 4 is never shorter than mt3. Sometimes pedal digit 4 is reduced to a vestige, other times, even within a genus, it is not. In any case, Lagerpeton belongs in this clade, a small biped at the acme of a  large, flat-headed, quadrupedal clade. It does not belong with dinosaurs or their short pedal digit 4 kin. In Lagerpeton, the astragalus flange rises in back of the tibia, not in the front, as in dinosaurs.

The way to separate the Euarchosauriformes from the Pararchosaurifomes
is to introduce protorosaurs, Youngina, Youngoides, Choristodera, Doswellia and the traditional archosauriformes, as demonstrated by the large reptile tree.

Mistaking Early Triassic bipedal lizard tracks for dinosauromorph tracks
Earlier we discussed the mistakes of Brusatte et al. (2012) who claimed that certain ichnites related to Rotodactylus in the Early Triassic belonged to lagerpetids, when in reality they belong to cosesaurids, in the ancestry of pterosaurs.

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.

References
Langer MC, Nesbitt SJ, Bittencourt JS and Irmis RB 2013.  Non-dinosaurian Dinosauromorpha.  Geological Society, London, Special Publications v.379, first published February 13, 2013; doi 10.1144/SP379.9 From: Nesbitt SJ, Desojo JB and Irmis RB eds) Anatomy, Phylogeny and Palaeobiology of Early Archosaurs and their Kin. Geological Society, London, Special Publications, 379, http://dx.doi.org/10.1144/SP379.9 # The Geological Society of London 2013.

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