When pre-primates split from pre-rodents

A quick look at two closely related taxa today.
Hapalodectes (IVPP V5235, Fig. 1; Paleocene. China) nests at the base of the clade of primates (lemurs through humans, Fig. 3). Notice the narrow, transverse premaxilla and large canine.

Figure 1. The IVPP V5235 specimen of Haplodectes. Note the large canine and small, transverse premaxilla, traits shared with higher primates.

Figure 1. The IVPP V5235 specimen of Hapalodectes. Note the large canine and small, transverse premaxilla, traits shared with higher primates.

On the other hand
Ptilocercus
(Fig. 2; extant, Thailand, the pen-tailed tree shrew) nests at the base of the clade of rodents and rabbits and kin. Notice the large premaxilla (yellow) and small canine (orange). This represents the genesis of gnawing teeth in this clade.

Figure 2. The skull of Ptilocercus, nesting at the base of the rodent/rabbit clade. Note the large premaxilla (yellow) and small canine (orange).

Figure 2. The skull of Ptilocercus, nesting at the base of the rodent/rabbit clade. Note the large premaxilla (yellow) and small canine (orange).

These mouse-sized arboreal taxa
are late survivors of an earlier Middle Jurassic radiation. Both have a complete circumorbital ring, atypical for most mammals.

Figure 3. Subset of the LRT focused on Primates and basal Glires.

Figure 3. Subset of the LRT focused on Primates and basal Glires.

 

Toxodon: now closer to kangaroos than to wombats

Figure 1. The skulls of Toxodon, Procoptodon and Interatherium resemble one another more than their post-crania might suggest. Now they nest together in the LRT (subset in figure 2).

Figure 1. The skulls of Toxodon, Procoptodon and Interatherium resemble one another more than their post-crania might suggest. Now they nest together in the LRT (subset in figure 2).

Another short one today
just to dash off a progress report as I wrestle with metatherian data. Like everyone else, I’m learning as I go. Toxodon and Eurygenium (Fig. 1) were always close to Interatherium, which was recently nested at the base of all kangaroos with the addition of the short-faced kangaroo, Procoptodon to the large reptile tree (LRT, 1258 taxa). Bulky, quadrupedal Toxodon and Eurgenium previously nested with quadrupedal wombats. 

The loss of pedal digit 1
found in kangaroos, interatheres and
Toxodon + Eurygenium turns out to be not a convergence, but a homoplasy as the Toxodon + Eurygenium node shifts over to the Interatherium node. All three are quadrupeds.

Now basal wombats with five pedal digits,
like the koala, no longer have four-toed taxa, like Eurygenium and Toxodon, separating them from their five-toed ancestors. 

Interatheres are getting to be more interesting. 

Figure 2. Subset of the large reptile tree focusing on the Metatheria. The tree is fully resolved, but many bootstrap scores under 50 indicate that only one or two characters separate those nodes with low scores. Scores higher than 50 are separated by three or more traits.

Figure 2. Subset of the large reptile tree focusing on the Metatheria. The tree is fully resolved, but many bootstrap scores under 50 indicate that only one or two characters separate those nodes with low scores. Scores higher than 50 are separated by three or more traits.

BTW
loss of pedal digit 1 also occurs alone in the wolf-like marsupial carnivore, the Tasmanian wolf, Thylacinus, by convergence.  By convergence, pedal digit 1 also shrinks in the bandicoot (Perameles) clade.

Geologically
western Gondwana (Africa + South America) separated from eastern Gondwana (Madagascar, India, Australia, Antartica) about 180 mya (Jurassic). That’s when the ancestors of South American Interatherium and Toxodon separated from the Australian ancestors of kangaroos. This is one way to estimate the antiquity of mammal clades.

Final thought for paleontologists and soon-to-be-paleontologists:
Reexamining data, like this, is good science. Making mistakes. like this, goes with the territory. Naiveté and enthusiasm go hand-in-hand. Apologies often follow. Gaining experience is a slog, but worthwhile when the puzzle pieces fit better in the end. More work often brings new insight. 

 

 

Dryolestes, a tiny mammal mandible with many molars

Figure 1. Having 7 or 8 molars is very unusual for mammals. So finding a close match for Dryolestes is easy, once you have Docodon and Amphitherium. Dryolestes is the most derived of these three.

Figure 1. Having 7 or 8 molars is very unusual for mammals. So finding a close match for Dryolestes is easy, once you have Docodon and Amphitherium. Late Jurassic Dryolestes is the most derived of these three based on the anterior lean of the coronoid process and the shamrock-shaped molars, reduced from their Middle and Late Jurassic relatives. 

With only the mandible + teeth to work with
(Fig. 1) the data on Dryolestes is too sparse to enter into the LRT, but having 8 molars in the Late Jurassic is atypical enough to make finding a close relative relatively easy—if you have Docodon and Amphitherium (Fig. 1) in your list. The best place to look for tiny Jurassic mammals with so many molars is within the Prototheria (Monotremata), which now includes extant toothless taxa.

Wikipedia offers
a cladogram that nests Dryolestes close to Amphitherium, but the next taxon at the next node is Vincelelestes, which has very few molars and large saber teeth and therefore is in no way related. Docodon does not appear on that cladogram. The plasticity of the tooth shapes is quite apparent here. Dryolestes looks like to was more interesting in sieving than in cracking beetle shells. But who knows?

All these taxa have been known for over 150 years. Wikipedia reports, “It has been suggested that this group [Dryolestoidea] is closely related to modern therian mammals.  Dryolestid dentition is thought to resemble the primitive mammalian dentition before the marsupial-eutherian differentiation and dryolestids are candidates to be the last common ancestor of the two mammalian subclasses.”

The burrowing placental, Necrolestes, is listed as a dryolestoid in Wikipedia.

References

wiki/Dryolestes
wiki/Dryolestidae
wiki/Dryolestoidea

 

Naked, horned and pocket gophers

Figure 1. Subset of the LRT focusing on the rabbit/rodent and kin clade where gophers nest with hedgehogs.

Figure 1. Subset of the LRT focusing on the rabbit/rodent and kin clade where gophers nest with hedgehogs.

In the large reptile tree (LRT, 1258 taxa, Fig. 1) the naked mole rat (genus: Heterocephalus, Fig. 2) nests with the hedgehog clade, one node off from the mouse/rat/clade. So the naked mole rat should be the  naked mole gopher.

Figure 1. The naked mole rat, Heterocephalus is closer to hedgehogs than to rats.

Figure 2. The naked mole rat, Heterocephalus is closer to hedgehogs than to rats.

Heterocephalus glaber (Rüppell 1842-5; 8-10cm) is the extant naked mole rat. It has a cold-blooded metabolism, lives underground, and can move backwards as fast as forward. Not the claws, but the teeth (protruding outside the lips) are used for digging. Heterocephalus is essentially hairless, lives in a colony dominated by a queen and may live up to 32 years in a low oxygen environment, or several times longer than related taxa.

Figure 2. Naked mole rat (Heterocephalus) skull in several view. The mandibles are disarticulated here, but the glenoid appears to be reduced to absent, providing great mobility to the jaws.

Figure 2. Naked mole rat (Heterocephalus) skull in several view. The mandibles are disarticulated here, but the glenoid appears to be reduced to absent, providing great mobility to the jaws.

Ceratogaulus hatcheri is the extinct horned gopher (Fig. 3). It nests with the naked mole rat in the LRT (Fig. 1).

Figure 3. Ceratogaulus, the extinct horned gopher

Figure 3. Ceratogaulus, the extinct horned gopher

Thomomys bottae (Figs. 4, 5) is the extant pocket gopher, another rodent nesting with hedgehogs.

Figure 4. Skull of Thomomys, the extant pocket gopher.

Figure 4. Skull of Thomomys, the extant pocket gopher. No large retroarticular process here.

These taxa look like rodents
but they nest with hedgehogs. So do we expand our concept of rodents (lumping)? Or make new clades (splitting)?

Figure 5. Skeleton of Thomomys, the pocket gopher.

Figure 5. Skeleton of Thomomys, the pocket gopher.

 

Rodentia is characterized by a single pair of continuously growing incisors in each of the jaws, as opposed to rabbits, which have two incisors.

Glires (Latin glīrēsdormice) is a clade consisting of rodents and lagomorphs (rabbits, hares, and pikas). In the LRT many more clades of small mammals nest with rabbits and rodents.

Euarchontoglires (synonymous with Supraprimates) is a clade of mammals, the living members of which belong to one of the five following groups: rodentslagomorphstreeshrewscolugos and primates. In the LRT rodents nest with primates, but not colugos.

References
Rüppell E 1842-5. Säugethiere aus der Ordnung der Nager, beobachtet im nordöstlichen Africa. Museum Senckenbergianum: Abhandlungen aus dem Gebiete der beschreibenden Naturgeschichte. 3: 99–101.

wiki/Hedgehogs
wiki/Erinaceus
wiki/Echinops
wiki/Naked_mole-rat

https://blogs.scientificamerican.com/tetrapod-zoology/african-mole-rats-so-much-more-than-just-the-naked-mole-rat/

Molecules vs morphology in mammals: Beck and Baillie 2018

Some published thoughts
on traits vs. molecules just out in the last week.

Beck and Baillie 2018 titled their paper: 
“Improvements in the fossil record may largely resolve the conflict between morphological and molecular estimates of mammal phylogeny.” No. Just the opposite. But you can see exactly where they put their faith… not in what they can see and measure.

From the abstract (annotated):
“Morphological phylogenies of mammals continue to show major conflicts with the robust molecular consensus view of their relationships.” True.

“This raises doubts as to whether current morphological character sets are able to accurately resolve mammal relationships, particularly for fossil taxa for which, in most cases, molecular data is unlikely to ever become available.” Just the opposite. Doubts should have been raised about molecular data, which can be influenced by local viruses. Only physical traits, i. e. the expression of activated molecules, resolves relationships, as the large reptile tree (LRT, 1255 taxa) attests. 

“We tested this under a hypothetical ‘best case scenario’ by using ancestral state reconstruction (under both maximum parsimony and maximum likelihood) to infer the morphologies of fossil ancestors for all clades present in a recent comprehensive molecular phylogeny of mammals, and then seeing what effect inclusion of these predicted ancestors had on unconstrained analyses of morphological data. We found that this resulted in topologies that are highly congruent with the molecular consensus, even when simulating the effect of incomplete fossilisation. Most strikingly, several analyses recovered monophyly of clades that have never been found in previous morphology-only studies, such as Afrotheria and Laurasiatheria.” In other words, we used our imaginations to make molecule phylogenies work, rather than considering the possibility that molecular phylogenies did not work. 

“Our results suggest that, at least in principle, improvements in the fossil record may be sufficient to largely reconcile morphological and molecular phylogenies of mammals, even with current morphological character sets.” They used far too few taxa. And they used suprageneric taxa. They avoided fossil taxa. This is omitting available data. 

This is not the way science is supposed to work.
So why was this published?

References
Beck RMD and Baillie C 2018. Improvements in the fossil record may largely resolve the conflict between morphological and molecular estimates of mammal phylogeny. bioRxiv doi:10.1101/373191. First posted online July 20, 2018.

Click to access 373191.full.pdf

The pink fairy armadillo joins the LRT as a glyptodont…

…not an armadillo.
The pink daily ‘armadillo’ (genus: Chlamyphorus) nests with the much larger glyptodont, Holmesina in the large reptile tree (LRT, 1255 taxa, subset Fig. 4), not with Dasypus novemcinctus, the extant llong-nosed armadillo nesting on the other side of the aardvark Orycteropus. Another fairy armadillo (genus: Calyptophractos) is also described here.

The pink fairy armadillos
(genus: Chlamyphorus trunca) and the greater fairy armadillo (genus: Calyptophractos retusus) are little glyptodonts. This is not heretical news (Fig. 1).

Figure 3. When glyptodonts were nested with armadillos, the fairy armadillos nested with extinct glyptodonts. Cladogram from xx

Figure 1. When glyptodonts were nested with armadillos, the fairy armadillos nested with extinct glyptodonts. Cladogram from Delsuc et al. 2016, a DNA analysis. No aardvarks were tested here.

Using DNA
(both ancient and modern) Delsuc et al. 2016 nested the fairy armadillo with the extinct glyptodont, Doedicurus (Fig. 1). We already know not to trust DNA evidence in paleontology, but in this case trait analysis supports something like this arrangement of taxa. The distance is not great either way.

Figure 2. DNA analysis by Möller-Krull et al. 2007 omits fossil taxa and aardvarks and arrives at this tree topology of extant edentates.

Figure 2. DNA analysis by Möller-Krull et al. 2007 omits fossil taxa and aardvarks and arrives at this tree topology of extant edentates.

Delsuc et al. 2016 nested fairy armadillos with glyptodonts
when they attempted to nest glyptodonts within the armadillo clade using DNA, omitting other fossil taxa.  I did not see LRT outgroups in their cladogram, nor did I see the aardvark.

Figure 3. Skulls of Holmesina and Calyptophractus compared.

Figure 3. Skulls of Holmesina and Calyptophractus compared. When they are together, the similarities are obvious.

Here in the LRT Calyptophractus is a phylogenetic miniature of Holmesina, with a shorter rostrum and expanded cranium (Fig. 3), along with its much smaller size and thinner scales. In lateral view the skulls are quite alike and distinct from all other edentates.

We know that aardvarks (genus: Orycteropus) nest with edentates because all the other possibilities were offered and found to be not as parsimonious (similar). Earlier we looked at the nesting of Holmesina and the phylogenetic fact that all aardvarks, armadillos and anteaters are derived from various types of glyptodonts.

Figure 2. Subset of the LRT focusing on the Edentata. Armored taxa are color tinted and their branches are thicker.

Figure 4. Subset of the LRT focusing on the Edentata. Armored taxa are color tinted and their branches are thicker.

References
Delsuc F et al. 2016. The phylogenetic affinities of the extinct glyptodonts. Current Biology 26(4):R155–R156.
Harlan R 1825. Annals of the Lyceum of Natural History of New York 1:235.
Möller-Krull M et al. 2007. Retroposed Elements and Their Flanking Regions Resolve the Evolutionary History of Xenarthran Mammals (Armadillos, Anteaters, and Sloths). Mol. Biol. Evol. 24 (11): 2573–2582. PDF
Yarrell W 1828. On the osteology of the Chlamyphorus truncatus of Dr. Harlan microform; in a letter to N.A. Vigors. Zoological Journal 3:544–554.

AKA
Pink Fairy Armadillo, Lesser Fairy Armadillo, Lesser Pichi Ciego, Pichiciego
http://www.iucnredlist.org/details/4704/0

Greater Fairy Armadillo, Burmeister’s Armadillo, Chacoan Fairy Armadillo, Greater Pichi Ciego: http://www.iucnredlist.org/details/4703/0

wiki/Pink_fairy_armadillo

https://www.amnh.org/explore/news-blogs/research-posts/study-finds-relationship-between-glyptodonts-modern-armadillos/

https://www.forbes.com/sites/shaenamontanari/2016/02/23/ancient-dna-from-extinct-glyptodont-reveals-it-was-a-really-big-armadillo/#2cb057ae287d

Juvenile Rhamphorhynchus and flightless pterosaur abstracts

Part 4
The following manuscripts are independently published online without peer-review at the DavidPetersStudio.com website. http://www.davidpetersstudio.com/papers.htm

Better to put them out there this way
than to let these works remain suppressed. Hope this helps clarify issues.


Peters D 2018g. First flightless pterosaur
PDF of manuscript and figures

Pterosaur fossils have been discovered all over the world, but so far no flightless pterosaurs have been reported. Here an old and rarely studied pterosaur fossil (Sos 2428) in the collection of the Jura Museum in Eichstätt, Germany, was re-examined and found to have a reduced pectoral girdle, small proximal wing elements (humerus, radius and ulna), three vestigial distal wing elements, the relatively longest pelvis of any pterosaur and the widest gastralia, or belly ribs. This discovery represents a unique morphology for pterosaurs. The Jura specimen lacked the wing size, forelimb muscularity and aerodynamic balance necessary to sustain flapping flight. It was a likely herbivore.


Peters D 2018h. First juvenile Rhamphorhynchus recovered by phylogenetic analysis
PDF of manuscript and figures
Standing seven to 44 centimeters in height, a growing list of 120+ specimens assigned to the pterosaur genus Rhamphorhynchus are known chiefly from the Solnhofen Limestone (Late Jurassic, southern Germany). An early study recognized five species and only one juvenile. A later study recognized only one species and more than 100 immature specimens. Phylogenetic analyses were not employed in either study. Workers have avoided adding small Solnhofen pterosaurs to phylogenetic analyses concerned that these morphologically distinct specimens were juveniles that would confound results. Here a large phylogenetic analysis that includes tiny Solnhofen pterosaurs tests that concern and seeks an understanding of relationships and ontogeny within the Pterosauria with a focus on Rhamphorhynchus. 195 pterosaurs were compiled with 185 traits in phylogenetic analysis. Campylognathoides + Nesodactylus were recovered as the proximal outgroups to the 25 Rhamphorhynchus specimens. The ten smallest of these nested at the clade base demonstrating phylogenetic miniaturization. Two Rhamphorhynchus had identical phylogenetic scores, the mid-sized NHMW 1998z0077/0001, and the much larger, BMNH 37002. These scores document a juvenile/adult relationship and demonstrate isometry during pterosaur ontogeny, as in the azhdarchid, Zhejiangopterus, and other pterosaurs. Rather than confounding results, tiny Solnhofen pterosaurs illuminate relationships. All descended from larger long-tailed forms and nested as transitional taxa at the bases of the four clades that produced all of the larger Late Jurassic and Cretaceous pterodactyloids. No long-tailed pterosaurs survived into the Cretaceous, so miniaturization was the key to pterosaur survival beyond the Jurassic.

These manuscripts benefit from
ongoing studies at the large reptile tree (LRT, 1256 taxa) in which taxon exclusion possibilities are minimized and all included taxa can trace their ancestry back to Devonian tetrapods.

Tritosauria and Shenzhoupterus abstracts

Part 3
The following manuscripts are independently published online without peer-review at the DavidPetersStudio.com website. http://www.davidpetersstudio.com/papers.htm

Better to put them out there this way
than to let these works remain suppressed. Hope this helps clarify issues.


Peters D 2018e. A new lepidosaur clade: the Tritosauria
PDF of manuscript and figures

Several lizard-like taxa do not nest well within the Squamata or the Rhynchocephalia. Their anatomical differences separate them from established clades. In similar fashion, macrocnemids and cosesaurids share few traits with putative sisters among the prolacertiformes. Pterosaurs are not at all like traditional archosauriforms. Frustrated with this situation, workers have claimed that pterosaurs appeared without obvious antecedent in the fossil record. All these morphological ‘misfits’ have befuddled researchers seeking to shoehorn them into established clades using traditional restricted datasets. Here a large phylogenetic analysis of 1253 taxa and 231 characters resolves these issues by opening up the possibilities, providing more opportunities for enigma taxa to nest more parsimoniously with similar sisters. Remarkably, all these ‘misfits’ nest together in a newly recovered and previously unrecognized clade of lepidosaurs, the Tritosauria or ‘third lizards,’ between the Rhynchocephalia and the Squamata. Tritosaurs range from small lizard-like forms to giant marine predators and volant monsters. Some tritosaurs were bipeds. Others had chameleon-like appendages. With origins in the Late Permian, the Tritosauria became extinct at the K–T boundary. Overall, the new tree topology sheds light on this clade and several other ‘dark corners’ in the family tree of the Amniota. Now pterosaurs have more than a dozen antecedents in the fossil record documenting a gradual accumulation of pterosaurian traits.


Peters, D. 2018f. New data on Shenzhoupterus chaoyangensis, an unusual Lower Cretaceous pterosaur
PDF of manuscript and figures

A recently described specimen of a new genus of pterosaur from the Lower Cretaceous Jiufotang Formation of northeastern China, Shenzhoupterus chaoyangensis, was assigned to the Chaoyangopteridae within the Azhdarchoidea. Originally the posterior skull was traced as an indistinct sheet with only a drop-shaped orbit piercing it at mid-height. That morphology would be atypical for pterosaurs, but a low orbit is found in azhdarchids. A first-hand observation provided new data. Here a new technique, known as Digital Graphic Segregation (DGS), enabled the identification of every bone in the chaotic jumble of the posterior skull and a new reconstruction of the specimen’s “face” in which the orbit was very high on the skull and otherwise more in accord with other pterosaurs. Other purportedly missing elements including the pelvis, prepubis, pteroid and sternal complex were also identified. A new reconstruction of Shenzhoupterus demonstrates very few synapomorphies with Chaoyangopterus, but several with tapejarids and dsungaripterids.


These manuscripts benefit from
ongoing studies at the large reptile tree (LRT, 1253 taxa) in which taxon exclusion possibilities are minimized and all included taxa can trace their ancestry back to Devonian tetrapods.

July 2011-July 2018: Marking 7 years of paleo-heresies.

On July 12, 2011
a new blogpost entitled, “Welcome to The Pterosaur Heresies” first appeared online. It was (and is) meant to be the newsletter for taxon additions to the large reptile tree (LRT, 1255 taxa) at ReptileEvolution.com. More complete explanations and documentation can be provided here than at ReptileEvolution.com.

Starting two days later (July 14, 2011) and for the next three days,
the several hypotheses of pterosaur origins were compared one with another.

About a week later (July 22, 2011)
a completely resolved family of pterosaurs was presented. This was the first one to include several specimens from all well-known genera and the first to include tiny Solnhofen pterosaurs, first listed by Peters 2007. Previously tiny pterosaurs had been ignored based on the false premise that they were juveniles of larger specimens. That is a disproved hypothesis that continues to make the rounds. And we said goodbye to the clade, “Pterodactyloidea” because now 4 clades are recovered that share all of the pterodactyloid-grade traits, while two others share some, but not all of those traits. Have other workers started to include tiny Solnhofen pterosaurs in their analyses? No.

On the last day of that first month (July 31, 2011)
a  phylogenetic analysis of just 235 taxa was presented that recovered a completely resolved and diphyletic Reptilia (= Amniota), with one branch, the new Lepidosauromorpha, containing turtles, pterosaurs and lepidosaurs and their many relatives. The other branch, the new Archosauromorpha, contained mammals, enaliosaurs, archosaurs and their many relatives. An amphibian-like reptile, Gephyrostegus was their last common ancestor.  Today, with more than 1000 additional taxa, the original topology from seven years ago remains unchanged. Have other workers started to include basal amphibian-like reptiles in their analyses? No.

In the seven years since July 2011
hundreds of exciting and heretical discoveries have been recovered. Some of these resolve long-standing problems by simply adding taxa. Others shed new light on topics that were not thought to be problems at all by simply adding taxa. Ironically, several other workers gained worldwide acclaim for ‘discovering’ relationships that were recovered in the LRT and promoted here years earlier. Still other workers continue to criticize the LRT, claiming it should have failed some time ago, but the LRT continues to grow.

Unfortunately,
a propagandistic pall was cast on the LRT, so most workers have ignored the taxon inclusion/exclusion suggestions offered here, leaving their work open to criticism from the ever-growing authority of the LRT.

Whatever the faults of the LRT,
the specimens included here need only be included in more focused analyses using independent character lists to test them. In other words, the faults don’t have to be employed, only the suggested taxa. When that happens, confirmation of the LRT has been the typical result. Why? Because the wide gamut and sheer number of taxa minimize the possibility of taxon exclusion, the number one problem in prior, less inclusive analyses. If you have a tetrapod of unknown affinity, test it here at the LRT.

One unexpected and disappointing discovery:
DNA analysis, the standard for crime-fighting and paternity questions, has not been able to replicate the results of wider trait studies. Rather, DNA studies lose their efficacy over large phylogenetic distances when compared to the trait-oriented LRT. Worse yet for paleontology, DNA cannot be used with most fossils. Unfortunately, many paleontologists still believe in the validity of DNA studies.

Figure 2. Dr. Sean Carroll and Dr. Antonis Rokas

Figure 1. Dr. Sean Carroll and Dr. Antonis Rokas

On that note…
Quoted from EvolutionNews.org, “Finally, a study published in Science in 2005 (Rokas and Carroll 2006) tried to use genes to reconstruct the relationships of the animal phyla, but concluded that “despite the amount of data and breadth of taxa analyzed, relationships among most [animal] phyla remained unresolved.” The following year, the same authors published a scientific paper titled, “Bushes in the Tree of Life,” which offered striking conclusions. The authors acknowledge that “a large fraction of single genes produce phylogenies of poor quality,” observing that one study “omitted 35% of single genes from their data matrix, because those genes produced phylogenies at odds with conventional wisdom.” The paper suggests that “certain critical parts of the [tree of life] may be difficult to resolve, regardless of the quantity of conventional data available.” The paper even contends that “the recurring discovery of persistently unresolved clades (bushes) should force a re-evaluation of several widely held assumptions of molecular systematics.”

I was not aware of that 2005 paper
before a few days ago. It needs to be more widely considered.

While other blogs journalistically report on the works of others,
the Pterosaur Heresies scientifically tests the work of others. That’s what sets it apart. That’s what makes it fun, interesting and rewarding. That’s what makes it controversial. Hopefully, that’s why you’re a subscriber. If, instead, you keep waiting for the LRT to crash and burn, well, that should have happened by now, don’t you think?

This July 2018,
seven years after it was started in 2011 with 235 taxa, there are 1000+ more taxa, all gradually blended in a tree topology that has been growing organically and with virtual complete resolution (some taxa known only from mandibles and other scraps are less resolved). Still, critics keep harping on the same perceived shortcomings (too many taxa, too few traits, not enough firsthand observation, lack of expertise)—while not harping on the shortcomings of traditional studies (principally taxon exclusion) that fail to produce gradually blended (= similar) sister taxa. There has always been a double standard at play, not only here, but for new hypotheses in geology, astronomy, physics, and paleontology. It’s universal and has been at work for centuries. It used to be that religious leaders led the charge against new ideas. Now we have PhDs trying to do the same.

Even scientists are not immune from this thing we call ‘human nature.’
Dr. J Ostrom complained about it, too. It’s human nature to follow authority, to go with the majority, and to suppress contra-indicators. Facts sometimes take decades to be widely accepted, and that’s just the way it is. It’s not acceptable, but that’s the way it is.

The beauty of science is
you, yes you can perform your own analysis to confirm or refute any analysis you read about here or anywhere. If I can do it… you can do it.

Thank you for your readership.
If there are subjects/taxa you want me to cover, or issues that need resolution, let me know. I look forward each day to corresponding with each and every one of you.

References
Peters D 2007. The origin and radiation of the Pterosauria. Flugsaurier. The Wellnhofer Pterosaur Meeting, Munich 27
Rokas A and Carroll SB 2006. Bushes in the Tree of Life. PLoS Biology, 4(11): 1899-1904.

refined-fine-tuned-placental-mammal-family-tree/

 

What is Periptychus carinidens?

Figure 1. Subset of the LRT focusing on the nesting of Periptychus.

Figure 1. Subset of the LRT focusing on the nesting of Periptychus.

Short answer:
In the large reptile tree (LRT, 1253 taxa, subset Fig. 1) Periptychus (Figs, 2–4) nests between basal phenacodonts like Phenacodus, Thomashuxleya and Pleuraspidotherium, and derived phenacodonts, like Gobiatherium + Arsinoitherium and Coryphodon + Uintatherium. These are all extinct herbivores from a clade that was recovered here first. Some derived taxa had ornate skull bumps/horns.

Previously known
as a condylarth from less complete materials (Cope 1881), the latest academic paper on Periptychus (Shelley, Williamson and Brusatte 2018) was still unable to determine closest relatives based on new data. No cladogram was presented. Sisters listed above were not listed in the text. Rather, the authors called it, “A robust, ungulate-like placental mammal.” 

Figure 2. Periptychus skull in 3 views.

Figure 2. Periptychus skull in 3 views ftom Shelley, Williamson and Brusatte 2018, colors added.

Think of Periptychus as a placental herbivore with very primitive feet…

Figure 3. Periptychus skeleton restored.

Figure 3. Periptychus skeleton restored from Shelley, Williamson and Brusatte 2018.

… and hands (no reduced digits). This mammal is remarkable for its long list of unremarkable traits.

Of course,
this was only the ‘warm-up act’ for the big, bizarre uintatheres to follow.

Figure 4. Manus and pes of Periptychus with some bones restored.

Figure 4. Manus and pes of Periptychus with some bones restored.

 

References
Cope ED 1881. The Condylarthra (Continued). American Naturalist 84;18: 892–906.
Shelley SL, Williamson TE and Brusatte SL 2018. The osteology of Periptychus carinidens: A robust, ungulate-like placental mammal (Mammalia: Periptychidae) from the Paleocene of North America. PLoS ONE 13(7): e0200132.

https://doi.org/10.1371/journal.pone.0200132