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

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.

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.

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 vestigeAn 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.

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

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9 thoughts on “Tulerpeton becomes the last common ancestor of all Reptilia (=Amniota)

  1. Yesterday we looked

    You looked. And then you didn’t look at the comments, which would have rendered this post obsolete before you wasted all this time and effort writing it.

    What is wrong with you? I thought you wanted to learn?

    as a basal reptile, rather than a basal tetrapod, which is the traditional nesting.

    As I told you, having it on the amniote stem is the more traditional nesting.

    The differences shift the nesting of Tulerpeton to the last common ancestor of all reptiles (= amniotes).

    Does it have a zero-length branch? Do you even know how to check that? And hasn’t it occurred to you that it’s much too old to be the last common ancestor of all amniotes?

    Gephyrostegus bohemicus, the taxon that held that node in the large reptile tree (LRT) for the last six years.

    Like Tulerpeton now, it didn’t come out at a node. It came out at the end of a branch. PAUP* cannot even do otherwise, and neither can TNT or any other program. So, did that branch at least have a length of zero?

    five phalanges on digit 5

    The taphonomic assumption you have to make is really very strange. Equally strange is what your reconstruction of the digit looks like. Sure, there are precedents for having short middle and long proximal and distal phalanges, but that only happens in extremely grasping feet like those of owls or chameleons, and then it happens in the whole foot, not just one digit while the others have normal proportions.

    You’ve reconstructed a Frankenstein monster, and you haven’t even noticed.

    Similar things hold for the cleithrum of Silvanerpeton and its first few rows of ventral scales, which you strangely depict together with the tail ribs…

    • David P. wrote: “as a basal reptile, rather than a basal tetrapod, which is the traditional nesting. David M. wrote: “As I told you, having it on the amniote stem is the more traditional nesting.” The amniote stem does not include amniotes = reptiles in the LRT. So all taxa on the amniote stem are basal tetrapods. And you know that. You’re just being argumentative. Over at Wikipedia:Tulerpeton, you point is made according to Lebedev and Coates 1995, and Coates 1996. Wikipedia also notes five later studies nested Tulerpeton lower on the basal tetrapod tree.

      David M. wrote: “Does it have a zero-length branch? Do you even know how to check that? And hasn’t it occurred to you that it’s much too old to be the last common ancestor of all amniotes?” I use Bootstrap Scores and in that transitional grade all scores are above 50 currently. Typically that means at least an additional 3 steps are necessary to shift taxa. Chronologically Gephyrostegus bohemicus (Westphalian) is much too young to be the common ancestor of all amniotes, and lancelets are still extant, so chronology is not a deal breaker in this case. Given the variation in amniotes known in the Viséan, Tulerpeton, as mentioned above, is just the right age to be the last common ancestor of all amniotes.

      re:branch and node: you are correct. All taxa are leaves on branches. But you get my point regarding the nesting of Gephyrostegus bohemicus.

      David M. wrote: “The taphonomic assumption you have to make is really very strange. Equally strange is what your reconstruction of the digit looks like. Sure, there are precedents for having short middle and long proximal and distal phalanges, but that only happens in extremely grasping feet like those of owls or chameleons, and then it happens in the whole foot, not just one digit while the others have normal proportions.” So, you don’t like strange… even if the PILs line up. Wondering about the grasping abilities of the pes lead us into the land of speculation. So, if you’re asking me to speculate, I can offer a weedy niche for Tulerpeton, every bit as dense, if not more so, than a forest canopy, where some, but not all denizens, have grasping digits. As mentioned above, short phalanges on digit 5 is the norm. What is not controversial are the long middle and penultimate phalanges on the lateral digit. That’s a given.

      David M. wrote: “You’ve reconstructed a Frankenstein monster, and you haven’t even noticed.” To the contrary. All the parts come from the same specimen. There is no chimaera here. I have rearranged the pieces to more closely match the in situ specimen (minimizing taphonomic drift) and putative sister taxa. So Tulerpeton is more like standard issue basal amniotes than originally thought. And more like standard issue basal tetrapods than originally thought. Give the strange original reconstruction of Lebedev and Coates, did you accuse them of creating a Frankenstein monster – so unlike any candidate sisters? Perhaps you should have done so.

      David M. wrote: “Similar things hold for the cleithrum of Silvanerpeton and its first few rows of ventral scales, which you strangely depict together with the tail ribs…” That’s another roadkill specimen that may need yet another look now that I’ve had more experience with other taxa that nest near it. It’s another very difficult fossil.

    • Darren, there was a time when you had to defend your thesis and you succeeded in whole or in part. That’s what I’m doing here. I’m happy to correct my erroneous interpretations. That makes good Science. I’m also able to note erroneous interpretations in the work of others. That’s also good Science. That you don’t believe that I am capable of that really tells us all more about you, than me.

  2. Sorry for the delay in getting to these comments.

    What you’re looking at is a hypothesis regarding placement of elements that have been scattered during taphonomy. I’m certainly open to alternatives. It doesn’t seem like you two are, but you’re willing to accept some strange interpretations by Lebedev and Coates.

    I found it strange that manual metacarpal 5 was oddly short.
    I also found it strange that pedal digit 5 or 6 had elongate phalanges. The short phalanges are not the odd aspect here, especially on a purported pedal digit 6 that ultimately disappears. See Gephyrostegus for comparison.
    I also found it odd that pedal digit 5 is absent while 1-4 and 6 were well represented. Yes, I realize that the lateral digit is folded under during taphonomy. I provide the above as a solution and show the parallel interphalangeal lines that are all continuous in this reconstruction.
    I note that the Lebedev and Coates reconstruction did not accurately repeat the in situ status of metatarsal 2 being larger than 3. Bits and pieces of metatarsal 1 reassembled continue the pattern making it the longest metatarsal with its tip aligned with 2 and 3. That’s an autapomorphy, but so would be having metatarsal 2 the longest.

    The curly posterior ilium shows Tulerpeton to be on its own evolutionary branch. Tulerpeton in any scenario has autapomorphies, so it is already derived beyond a plesiomorphic basal amniote in the late Devonian.

    How do you get from non-claws to claws? Tulerpeton shows us. This is why I call Silvanerpeton, Tulerpeton, Gephyrostegus and other related taxa amphibian-like reptiles. They don’t look like reptiles. Based on phylogenetic bracketing, they lay eggs like reptiles.

    Finally, the appearance of Tulerpeton in the latest Devonian precedes the wide variety of reptiles in the Viséan and succeeds the Middle Devonian footprints. So it makes sense that the origin of amphibian-like reptiles happened about then.

    I would love to avoid raising the ire of you two, but if something ain’t right, and I think I can make it right, I’ve got to report that. I make mistakes, but I also expose mistakes that others appear to gloss over. It’s okay to raise objections. I appreciate it when you two do so, whether you’re right or wrong. That means, it’s also okay for me to raise objections, even if I’m wrong. This time I stand by my reconstruction. Future discoveries will tip the balance.

    • I found it strange that manual metacarpal 5 was oddly short.

      Go try to distinguish phalanges, metapodials and distal mesopodials in Acanthostega or Ichthyostega. I’ll wait.

      I also found it strange that pedal digit 5 or 6 had elongate phalanges. The short phalanges are not the odd aspect here, especially on a purported pedal digit 6 that ultimately disappears.

      You assume that the pedal digits are I–V + postminimus, like in the hand. What if they’re prehallux + I–V instead?

      What if the question doesn’t even make sense? It doesn’t seem to in Acantho- or Ichthyostega

      I also found it odd that pedal digit 5 is absent while 1-4 and 6 were well represented. Yes, I realize that the lateral digit is folded under during taphonomy.

      No, it’s gone. It rotted loose or was eaten by a passing fish. Most fossils are fossils of rotting corpses, not of freshly dead animals.

      I provide the above as a solution and show the parallel interphalangeal lines that are all continuous in this reconstruction.

      Given the fact that this animal didn’t walk on land, would it even need such things? I also note that your interphalangeal lines are very often only approximately continuous; this is no exception – look closer.

      I note that the Lebedev and Coates reconstruction did not accurately repeat the in situ status of metatarsal 2 being larger than 3.

      I’ll check tomorrow, the paper’s in the office.

      The curly posterior ilium shows Tulerpeton to be on its own evolutionary branch.

      …nicely contradicting your claim that it’s an ancestor of Amniota.

      Tulerpeton in any scenario has autapomorphies

      Not in yours, where it’s an ancestor of something known!

      I would love to avoid raising the ire of you two, but if something ain’t right, and I think I can make it right, I’ve got to report that.

      Oh, I sympathize with that! The problem is that you don’t stop and wonder if it really ain’t right or if you’ve just misunderstood something because your access to literature is so erratic.

      Have you read Laurin et al. (2000) yet?

      • Also… morphological evolution doesn’t happen at some kind of constant rate. You can’t draw a straight line from the Middle Devonian footprints to late Viséan animals that are on the amniote stem (if the lissamphibians are temnospondyls) and use it to interpolate what happened in between.

      • David M. wrote (below): “Also… etc. ” You misinterpret the situation. No one argues for a straight line. I do argue for the realm of chronological and phylogenetic possibility. In the LRT lissamphibians are not temnospondyls. Diplovertebron and Eucritta are taxa near the base of the lepospondyl/amniote split, both with ghost lineages into the Devonian.

  3. Last things first, then in written order:
    I have not read Laurin et al 2000 yet, but I was able to find online correspondence on that paper from Coates and Ruta 2000 who brought up several issues. Following that was the Laurin, Girondot and deRicqles reply which ended with, “We suggest that the next step in this debate is for other scientists to perform phylogenetic analyses designed to test the origin of lissamphibians.” That’s what I’m doing.

    David M. wrote: “Go try to distinguish phalanges, metapodials and distal mesopodials in Acanthostega or Ichthyostega. I’ll wait.” As you know, this can be a guessing game. I provide one solution that may be correct, partially correct or totally incorrect. Providing a solution is part of the debate, and should be welcomed.

    David M. wrote: “You assume that the pedal digits are I–V + postminimus, like in the hand. What if they’re prehallux + I–V instead?” Given the data, I did assume 1-5+6. It seemed reasonable given the pretty close match to basal amniotes and what little we know of basal tetrapods. Again, it’s one solution that should be considered.

    David M. wrote: “What if the question doesn’t even make sense? It doesn’t seem to in Acantho- or Ichthyostega…” Humans are pattern-seeking tetrapods. What I’ve presented seems to make sense, at present. More data can change things, and that’s the process of Science.

    David M. wrote: “No, it’s gone. It rotted loose or was eaten by a passing fish. Most fossils are fossils of rotting corpses, not of freshly dead animals.” That is indeed the current paradigm. But what if it is not correct? If so, I provide a new solution. It struck me as odd that a middle finger was missing while the surrounding fingers were not. And I realize the manus is folded over at that point. If the paradigm is true, hopefully another specimen will show it more clearly and I will withdraw this hypothesis. One has to admit, when the manus/forefin of Devonian sacropterygians /transtional tetrapods are layer out in a row, Tulerpeton stands out as the oddity. But with the present reconstruction, it fits rather neatly (= fewest changes) with Silvanerpeton and Gephyrostegus. Since no one noticed that before, I brought it to the table for consideration.

    David M. wrote: “Given the fact that this animal didn’t walk on land, would it even need such things? I also note that your interphalangeal lines are very often only approximately continuous; this is no exception – look closer.” At this transitional stage in tetrapod evolution, there may have been a transitional substrate, like weedy water or soggy land, that Tulerpeton was adapted to. Contra your note, the interphalangeal lines are quite straight and continuous. If there are exceptions, and there are exceptions throughout the Tetrapoda, then that’s okay. It’s a pattern, not a rule, as I reported in 2000.

    David M. wrote: “…nicely contradicting your claim that it’s an ancestor of Amniota.” From what data I am aware of the curly posterior ilium is not present in any other basal tetrapods. So it doesn’t point elsewhere. It’s an autapomorphy. Given that Tulerpeton is a single specimen representing millions of undiscovered specimens at that transitional grade, this much variation is possible and okay. It doesn’t rock the boat… yet. But it could. There is always the possibility of a better candidate being discovered.

    David M. wrote: “Not in yours, where it’s an ancestor of something known!” At present, yes, Tulerpeton is a better candidate for the last common ancestor of all Lepidosauromorpha + Archosauromorpha in the LRT. It shares some traits with basal members of both clades that are not found in Gephyrostegus bohemicus, the last best candidate for that position.

    David M. wrote: “Oh, I sympathize with that! The problem is that you don’t stop and wonder if it really ain’t right or if you’ve just misunderstood something because your access to literature is so erratic.” My access to the literature is not complete, true. I discover things naively bit by bit, fitting the puzzle pieces in when I have them. So, I am always behind the times. This parallels the whole of paleontology where specimens are discovered not in the order they were evolved, but in an erratic and random manner. Like most paleontologists, I’m stymied and make mistakes on occasion. I disagree with your contention that I “don’t stop and wonder if it really ain’t right, etc.” I do that all the time. But it doesn’t happen until I see that a discontinuity has developed. In that regard, I’m just like every other paleontologist. I report discontinuities and possible errors so that others may check their own work against the new solutions. And that’s good Science. Right? That I have gone back and made changes to previously published solutions falsifies your claim outright.

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