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Tulerpeton becomes the last common ancestor of all Reptilia (=Amniota)

Friday, February 24, 2017 18:12
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(Before It's News)

Yesterday we looked at the nesting of Tulerpeton (Lebedev 1984; Latest Devonian; PIN 2921/7) as a basal reptile, rather than a basal tetrapod, which is the traditional nesting.

I thank
Dr. Michael Coates for sending a pdf of his 1995 study of Tulerpeton. From the improved data I was able to make new reconstructions of the manus and pes. The differences shift the nesting of Tulerpeton to the last common ancestor of all reptiles (= amniotes). replacing Gephyrostegus bohemicus, the taxon that held that node in the large reptile tree (LRT) for the last six years.

Figure 1. Tulerpeton parts from Lebedev and Coates 1995 here colorized and newly reconstructed. Manus and pes enlarged in figure 2. ” data-medium-file=”https://pterosaurheresies.files.wordpress.com/2017/02/tulerpeton_insitu_5881.jpg?w=584&h=584?w=300″ data-large-file=”https://pterosaurheresies.files.wordpress.com/2017/02/tulerpeton_insitu_5881.jpg?w=584&h=584?w=584″ class=”size-full wp-image-26221″ src=”https://pterosaurheresies.files.wordpress.com/2017/02/tulerpeton_insitu_5881.jpg?w=584&h=584″ alt=”Figure 1. Tulerpeton parts from Lebedev and Coates 1995 here colorized and newly reconstructed. Manus and pes enlarged in figure 2.” width=”584″ height=”584″ srcset=”https://pterosaurheresies.files.wordpress.com/2017/02/tulerpeton_insitu_5881.jpg?w=584&h=584 584w, https://pterosaurheresies.files.wordpress.com/2017/02/tulerpeton_insitu_5881.jpg?w=150&h=150 150w, https://pterosaurheresies.files.wordpress.com/2017/02/tulerpeton_insitu_5881.jpg?w=300&h=300 300w, https://pterosaurheresies.files.wordpress.com/2017/02/tulerpeton_insitu_5881.jpg 588w” sizes=”(max-width: 584px) 100vw, 584px” />

Figure 1. Tulerpeton parts from Lebedev and Coates 1995 here colorized and newly reconstructed. Manus and pes enlarged in figure 2. Note the in situ placement of the pedal phalanges. The clavicle is shown as originally published and withe the ventral view reduced in width to compare its unchanged length to the original lateral view image. 

In the new reconstruction
only the manus retained 6 digits, with the lateral sixth digit a vestige. The pes has a new reconstruction with only 5 digits, very much in the pattern of Gephyrostegus bohemicus. Both have five phalanges on digit 5. In the new reconstructions all of the PILs (Peters 2000) line up in sets.

Figure 2. Tulerpeton manus and pes in situ, reconstructed by Lebdev and Coates 1995 and newly reconstructed here. ” data-medium-file=”https://pterosaurheresies.files.wordpress.com/2017/02/tulerpeton_manus_pes.jpg?w=584&h=535?w=300″ data-large-file=”https://pterosaurheresies.files.wordpress.com/2017/02/tulerpeton_manus_pes.jpg?w=584&h=535?w=584″ class=”size-full wp-image-26219″ src=”https://pterosaurheresies.files.wordpress.com/2017/02/tulerpeton_manus_pes.jpg?w=584&h=535″ alt=”Figure 2. Tulerpeton manus and pes in situ, reconstructed by Lebdev and Coates 1995 and newly reconstructed here. ” width=”584″ height=”535″ srcset=”https://pterosaurheresies.files.wordpress.com/2017/02/tulerpeton_manus_pes.jpg?w=584&h=535 584w, https://pterosaurheresies.files.wordpress.com/2017/02/tulerpeton_manus_pes.jpg?w=150&h=138 150w, https://pterosaurheresies.files.wordpress.com/2017/02/tulerpeton_manus_pes.jpg?w=300&h=275 300w, https://pterosaurheresies.files.wordpress.com/2017/02/tulerpeton_manus_pes.jpg 588w” sizes=”(max-width: 584px) 100vw, 584px” />

Figure 2. Tulerpeton manus and pes in situ, reconstructed by Lebdev and Coates 1995 and newly reconstructed here with PILs added. Note the broken mt5 and the reinterpretation of the squarish elements as phalanges, not distal carpals. The tibiale is rotated 90º to cap the tibia. 

Lebedev and Coates report:
“A cladistic analysis indicates that Tulerpeton is a reptilomoprh stem-group amniote and the earliest known crown-group tetrapod. The divergence of reptilomorphs from batrachomorphs (frogs and kin) occurred before the Devonian Carboniferous boundary. Polydactyly persisted after the evolutionary divergence of the principal lineages of living tetrapods. Tulerpeton was primarily air-breathing.” They did not test Silvanerpeton, Gephyrostegus, Eldeceeon or Urumqia, which all now nest as proximal kin to Tulerpeton.

Autapomorphies
Manual digit 6 is present as a vestige. An anocheithrum (small bone atop the cleithrum) is present. Metatarsal 1 in Tulerpeton is the largest in the set. The posterior ilium rises. The femur has a large, sharp, fourth (posterior) trochanter.

Scales
on Tulerpeton are also found similar in size and number are also found in related taxa.

Taxon exclusion
and digital graphic segregation AND reconstruction AND comparative anatomy all contributed to the new data scores. As usual, I have not seen the specimen, but I did add it to a large gamut data matrix, the likes of which are not typically employed.

Figure 1. Silvanerpeton and Gephyrostegus to the same scale. Each of the two frames takes five seconds. Novel traits are listed. This transition occurred in the early Viséan, over 340 mya. Gephyrostgeus is more robust and athletic with a larger capacity to carry and lay eggs. ” data-medium-file=”https://pterosaurheresies.files.wordpress.com/2015/10/basal-amniote1.gif?w=584&h=501?w=300″ data-large-file=”https://pterosaurheresies.files.wordpress.com/2015/10/basal-amniote1.gif?w=584&h=501?w=584″ class=”size-full wp-image-20686″ src=”https://pterosaurheresies.files.wordpress.com/2015/10/basal-amniote1.gif?w=584&h=501″ alt=”Figure 1. Silvanerpeton and Gephyrostegus to the same scale. Each of the two frames takes five seconds. Novel traits are listed. This transition occurred in the early Viséan, over 340 mya. Gephyrostgeus is more robust and athletic with a larger capacity to carry and lay eggs.” width=”584″ height=”501″ />

Figure 3. Silvanerpeton and Gephyrostegus to the same scale. Each of the two frames takes five seconds. Novel traits are listed. These two give some idea about the size and shape of Tulerpeton. 

References
Coates MI and Ruta M 2001 (2002). Fins to limbs: What the fossils say. Evolution & Development 4(5): 390–401.
Lebedev OA 1984. The first find of a Devonian tetrapod in USSR. Doklady Akad. Navk. SSSR. 278: 1407–1413.
Lebedev OA and Clack JA 1993. Upper Devonian tetrapods from Andreyeva, Tula Region, Russia. Paleontology36: 721-734.
Lebedev OA and Coates MI 1995. postcranial skeleton of the Devonian tetrapod Tulerpeton curtum Lebedev. Zoological Journal of the Linnean Society. 114 (3): 307–348.
Peters D 2000. Description and Interpretation of Interphalangeal Lines in Tetrapods. Ichnos, 7: 11-41

wiki/Tulerpeton



Source: https://pterosaurheresies.wordpress.com/2017/02/25/tulerpeton-becomes-the-last-common-ancestor-of-all-reptilia-amniota/

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