The Phonodus-Bolosaurus-Bashkyroleter connection

This post might be boring.
These are the unpopular, rarely studied plain-looking reptiles that ultimately gave rise to many of the most interesting clades.

Bolosaurids
are rarely studied, rarely included in phylogenetic analyses and little has been published on them. Bolosaurus and Belebey are the classic specimens. Long-legged Eudibamus has been added to this clade by traditional workers (Berman et al. 2000), but the large reptile tree nests it instead with basal diapsids, like long-legged Petrolacosaurus.

The busiest and most difficult corner
of the large reptile tree always seemed to be between Milleretta and Macroleter (Fig. 1).This subset of the tree also includes many previous enigmas here resolved, including  turtles.

Figure 1. A subset of the large reptile tree focusing on the taxa between Milleretta and Lepidosauriformes, perhaps the most difficult corner of the large reptile tree.

Figure 1. A subset of the large reptile tree focusing on the taxa between Milleretta and Lepidosauriformes, perhaps the most difficult corner of the large reptile tree.

Phonodus was originally considered a procolophonid.
(Modesto et al. 2010). Here (Fig. 2) Phonodus nests close to procolophonids, but closer to bolosaurids. As an Early Triassic taxon, Phonodus represents a late surviving member of a Late Pennsylvanian/Earliest Permian radiation that produced Early Permian diadectids and others. Based on its unusual teeth, Phonodus was highly derived.

Figure 1. Phonodus tracing. This turns out to be a basal bolosaurid.

Figure 2. Phonodus tracing. This turns out to be a basal bolosaurid, close to procolophonids. Note the deeply excavated squamosal. The naris was originally overlooked. 

A related taxon
Bashkyroleter (Fig. 3) was originally considered a nyctoleterid parareptile (not a valid clade). Here (Fig. 1) Bashkyroleter is basal to the bolosaur/diadectid/procolophon clade and pareiasaur/turtle clade AND the remainder of the lepidosauromorpha, including the lanthanosuchids proximally. So, it is a key taxon, largely overlooked except for one paper (Müller and Tsuji 2007) on reptile auditory capabilities.

Yes,
this solidification of the large reptile tree involved some topology changes. Science is self correcting. New data brings new insights. One of these new insights involved Bashykyroleter and a previously overlooked connection of the lateral to the naris. (Fig. 2).

Figure 2. Bashkyroleter appears to have a small naris/lacrimal connection.

Figure 3. Bashkyroleter appears to have a small naris/lacrimal connection as shown above. If anyone has a dorsal, occipital  or palatal view of this taxon, please send it along. Another deeply embayed squamosal. 

References
Berman, DS, Reisz RR, Scott D, Henrici AC, Sumida SS and Martens T 2000. Early Permian bipedal reptile. Science 290: 969-972.
Modesto SP, Scott DM, Botha-Brink J and Reisz RR 2010. A new and unusual procolophonid parareptile from the Lower Triassic Katberg Formation of South Africa. Journal of Vertebrate Paleontology 30 (3): 715–723. doi:10.1080/02724631003758003.
Müller J and Tsuji LA 2007. Impedance-Matching Hearing in Paleozoic Reptiles: Evidence of Advanced Sensory Perception at an Early Stage of Amniote Evolution. PLoS ONE 2 (9): e889. doi:10.1371/journal.pone.0000889. PMC 1964539. PMID 17849018

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