Carnotaurus joins the LRT

Everyone knows Carnotaurus
(Fig. 1; Bonaparte 1985, Bonaparte, Novas and Coria 1990), the slender theropod with skull horns. In the large reptile tree (LRT, 1391 taxa) Carnotaurus nests with Majungasaurus, members of the first clade of giant theropods, the one that includes Spinosaurus, Allosaurus, Ceratosaurus and many others.

That comes as no surprise.
The only contribution I can make to this popular dinosaur is to note the horns arise from laterally extended lacrimals and prefrontals, not laterally extended frontals, as originally proposed (Fig. 1). In stating this, I may be late to the party. If others have already published on this bit of trivia, I am not aware of it. If so, let me know.

Figure 1. Carnotaurus skull. Note the traditional frontals are much reduced here. The horns are comprised of the lacrimals + prefrontals.

Figure 1. Carnotaurus skull from Bonaparte, Novas and Coria 1990 with colors added. Note the traditional frontals are much reduced here. Here the horns are comprised of the lacrimals + prefrontals in patterns typical of basal theropods.

Carnotaurus sastrei (Bonaparte 1985; Bonaparte, Novas and Coria 1990; Late Cretaceous, 70 mya; 7.5m in length) is an abelisaurid theropod dinosaur related to MajungasaurusCarnotaurus had a shorter, upturned snout, a shorter mandible, frontal horns, a deeper jugal, a narrower skull (below the horns) and a down-turned naris.

References
Bonaparte JF 1985. A horned Cretaceous carnosaur from Patagonia. National Geographic Research. 1 (1): 149–151.
Bonaparte JF, Novas FE and Coria RA 1990. Carnotaurus sastrei Bonaparte, the horned, lightly built carnosaur from the Middle Cretaceous of Patagonia. Contributions in Science. 416: 1–41. PDF

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Coeruleodraco: Traditional choristodere mistakes resurface

Occasionally within the Archosauriformes
the antorbital fenestra disappears. That is the case with the clade Choristodera, which Wikipedia describes as “an extinct order of semiaquatic diapsid reptiles. Cladists have placed them between basal diapsids and basal archosauromorphs, but the phylogenetic position of Choristodera is still uncertain.” 

That is so unnecessarily vague.
Just run the analysis. In the large reptile tree chorisotderes are derived from phylogenetically miniaturized proterosuchians like the BPI 2871 specimen and its sister Elachistosuchus.

Figure 1. Coeruleodraco skull as originally interpreted (below) and interpreted here (colors). This is a traditional error. Also note the remnants of an antorbital fenestra in this phylogenetically miniaturized taxon. The maxilla continues posterior to the orbit as in other choristoderes.

Figure 1. Coeruleodraco skull as originally interpreted (below) and interpreted here (colors). This is a traditional error. Also note the remnants of an antorbital fenestra in this phylogenetically miniaturized taxon. The maxilla continues posterior to the orbit as in other choristoderes. Firsthand access does not guarantee better interpretations.

 

Matumoto, Dong, Wang and Evans 2018
bring us a new genus of short-snouted, small choristodere, Coeruleodraco jurassicus (Fig. 1; Late Jurassic). The authors use a ‘by default’ very distant outgroup for their choristodere cladogram: the basal diapsids, Petrolacosaurus and Araeoscelis, because “Outgroup choice is problematic for Choristodera, because the position of the group within Diapsida remains uncertain.” The LRT solved that problem years ago and posted it online. Unfortunatley, the authors did not test the listed outgroup taxa. That’s all they had to do.

Figure 2. Dorsal, lateral and palatal views of BPI 2871 with bones colorized above. Below, reconstructed images of BPI 2871 tracings. It is more complete than illustrated by Gow 1975. Click to enlarge. Note the tiny remnant of the antorbital fenestra. The squamosal has been broken into several parts.

Figure 2. Dorsal, lateral and palatal views of BPI 2871 with bones colorized above. Below, reconstructed images of BPI 2871 tracings. It is more complete than illustrated by Gow 1975.Note the tiny remnant of the antorbital fenestra in this phylogenetically miniaturized proterosuchid, basal to Choristodera.

A traditional mistake associated with choristoderes
is the mislabeling of the nasals as the prefrontals (Fig. 1). Both Coeruleodraco and outgroup taxa, like the BPI 2870 specimen demonstrate the ascending process of the premaxilla extends beyond the naris. That it becomes detached from the toothy lateral processes in Champsosaurus (Fig. 3) does not turn the premaxilla into a nasal. We looked at that earlier here and once again, it is due to the exclusion of taxa that clarify the issue. Choristodere workers are not looking at these outgroup taxa for guidance or analysis.

Figure 2. Champsosaurus skull with premaxilla in yellow.

Figure 3. Champsosaurus skull with premaxilla in yellow.

The authors also messed up the finger identification.
The original interpretation of the Coeruleodraco manus (Fig. 4) misidentified the lateral and medial digits along with the olecranon and ulna (violet), which extends behind the humerus as in all other tetrapods. DGS revealed the middle phalanges of manual digit 4 behind the others. The apparently short digit 4 becomes the longest digit when reconstructed (Fig. 4). This matches the manus of other choristoderes.

Figure 3. Manus of Coeruleodraco as originally identified and repaired and reconstructed in color.

Figure 4. Manus of Coeruleodraco as originally identified and repaired and reconstructed in color. Note frame that includes middle phalanges of digit 4. Digit 5 also has a semi-buried element.

Yes, I see things in fossils that others don’t see.
These are just a few of the many examples. In science it’s okay to point out where others have missed things, and the only way to convey that data over the Internet is by tracing and publishing photos (Fig. 4). Others are free to confirm or refute.

Firsthand access does not guarantee better interpretations.
It is important to understand what sister taxa are present and what traits they present. Without a good cladogram answers will not arrive. If there is any question, as in Champsosaurus and Coeruleodraco it’s okay to look at sister taxa for guidance.

Choristoderes are archosauriformes
in which the antorbital fenestra is reduced to absent. Others, like the Wikipedia authors, Matsumoto, Dong, Wang and Evans, who look only at a list of traits present or absent in a taxon are “Pulling a Larry Martin.” That’s a common problem that leads to taxon exclusion. The LRT is a science experiment that you can confirm or refute yourself. It’s time to put the choristodere enigma to rest.

References
Matsumoto R, Dong L, Wang Y and Evans SE 2019. The first record of a nearly complete choristodere (Reptilia: Diapsida) from the Upper Jurassic of Hebei Province, People’s Republic of China, Journal of Systematic Palaeontology
DOI:10.1080/14772019.2018.1494220

Thanks to co-author, Dr. S. Evans,
for sending a PDF link to the paper. I sent her a pdf of the LRT noting that it provided outgroups for choristoderes back to Devonian tetrapods, but no reply accompanied the pdf link.

wiki/Coeruleodraco

Enigmatic Teraterpeton understood, at last, with better data

Finally
some photographic skull material has appeared online for Teraterpeton (Fig. 1). Not sure when these first appeared. Could have been years ago. I have not been searching until a day or two ago (see below).

First added
to the large reptile tree (LRT, 1371 taxa) on the basis of drawings by Sues 2003, the long rostrum and antorbital fenestra + the infilling of the lateral temporal fenestra of Teraterpeton  are traits that don’t go together anywhere else on anyone’s cladogram. Sues considered Teraterpeton an archosauromorph nesting with short-snouted Trilophosaurus (Figs. 1, 3).

In the LRT
Trilophosaurus is a rhynchocephalian lepidosaur nesting between derived sphenodontids, like short-snouted Sapheosaurus, and primitive rhynchosaurs, like short-snouted Mesosuchus. All related taxa have a diapsid-like temple architecture, even though the new clade Diapsida (Petrolacosaurus and kin) is restricted to members of the Archosauromorpha in the LRT. Lepidosaurs with a diapsid architecture have their own clade name: “Lepidosauriformes.” Details here and here.

The latest thinking identifies the large hole in the rostrum of Teraterpeton
that extends nearly to the orbit as a naris alone, not a combination of naris + antorbital fenestra. Here (Fig. 1) a broken strut-like bone lying atop the slender maxilla appears to have separated a naris from an antorbital fenestra in vivo. Even so, the present scoring for Teraterpeton with an antorbital fenestra without a fossa does not nest it with other taxa having an antorbital fenestra with or without a fossa.

Figure 1. Skulls of Teraterpeton and Trilophosaurus compared.

Figure 1. Skulls of Teraterpeton and Trilophosaurus compare well aft of the orbit, not so much below the orbit or in the rostrum.

This would not be the first time
an antorbital fenestra appeared in a lepidosaur. Pterosaurs and their ancestors, the fenestrasaurs, also have this trait by convergence with several other tetrapod taxa.

Comparing Trilophosaurus to Teraterpeton
(Fig. 1) is difficult until you get to the postorbital region of the skull. Then it’s a good match. Trilophosaurus has a reduced rostrum, a small naris, a robust maxilla and no hint of an antorbital fenestra. But like Teraterpeton alone, the lateral temporal fenestra found in all related taxa, is infilled with a large flange of the quadrate. Even so, the crappy character list for the LRT is able to nest these two taxa together.

Trilophosaurus and Teraterpeton nest with
the distinctively different Shringasaurus and Azendohsaurus in the LRT. The large variety in their morphologies hints at a huge variation yet to be found here. This is yet one more case where a list of traits may fail you, but a suite of several hundred traits will eliminate all other possibilities by a statistical process known as maximum parsimony. While the parsimony is minimal in this clade, it is still more than any other candidate taxa can offer from a list that has grown to over 1300.

A recent abstract on Teraterpeton
by Pritchard and Sues 2016 bears a review.

“Teraterpeton hrynewichorum, from the Upper Triassic (Carnian) Wolfville Formation of Nova Scotia, is one of the more unusual early archosauromorphs, with an elongate edentulous snout, transversely broadened and cusped teeth, and a closed lateral temporal fenestra. Initial phylogenetic analyses recovered this species as the sister taxon to Trilophosaurus spp. New material of Teraterpeton includes the first-known complete pelvic girdle and hind limbs and the proximal portion of the tail. These bones differ radically from those in Trilophosaurus, and present a striking mosaic of anatomical features for an early saurian.”

I agree completely, which makes solving this mystery so intriguing, and one perfectly suited to the wide gamut of the LRT.

The ilium has an elongate, dorsoventrally tall anterior process similar to that of hyperodapedontine rhynchosaurs

In all cladograms trilophosaurs are close to rhynchosaurs.

The pelvis has a well-developed thyroid fenestra, a feature shared by Tanystropheidae, Kuehneosauridae, and Lepidosauria. 

These taxa all nest within the Lepidosauriformes in the LRT. Mystery solved.

Figure 1. Azendohsaurus skull reconstructed with two premaxillary teeth, not four.

Figure 2. Azendohsaurus skull reconstructed with two premaxillary teeth, not four.

“The calcaneum is ventrally concave, as in Azendohsaurus”. 

Teteraterpeton and Trilophosaurus nest as sisters to Azendohsaurus (Fig. 2)  in the LRT.

The fifth metatarsal is proximodistally short, comparable to the condition in Tanystropheidae.” 

This condition is also found in lepidosaur tritosaur fenestrasaurs, including pterosaurs. Tanystropheidae nest as tritosaurs in the LRT. Mystery solved.

“Much as in the manus, the pedal unguals of Teraterpeton are transversely flattened and dorsoventrally deep.” 

The unguals of Trilophosaurus are also exceptionally deep and transversely flat.

“Phylogenetic analysis of 57 taxa of Permo-Triassic diapsids and 315 characters supports the placement of Teraterpeton as the sister-taxon of Trilophosaurus in a clade that also includes Azendohsauridae and, rather unexpectedly, Kuehneosauridae.”

Add taxa and the unexpected kuehneosaurs will drift to a more basal node.

“The mosaic condition in Teraterpeton underscores the importance of thorough taxon sampling for understanding the dynamics of character change in Triassic reptiles and the use of apomorphies in identifying fragmentary fossils.”

The term ‘mosaic’ is misleading. In the LRT there are no closer sisters to Teraterpeton than Trilophosaurus, and then, rather obviously, the similarities are immediately obvious only in the cheek region, distinct from all other taxa in the LRT.

Figure 2. Trilophosaurus has filled in the lateral temporal fenestra, reduced the orbit and increased the upper temporal fenestra, among other differences with Azendohsaurus.

Figure 3. Trilophosaurus has filled in the lateral temporal fenestra, reduced the orbit and increased the upper temporal fenestra, among other differences with Azendohsaurus.

Forcing Teraterpeton
back to long-snouted clades with an antorbital fenestra, like the Diandongosuchus clade, adds a minimum of 11 extra steps to the LRT.

Key to understanding
the lepidosaur nature of these taxa involves first understanding that the first dichotomy in the clade Reptilia separates the new Archosauromorpha from the new Lepidosauromorpha. Until someone else does this and it becomes consensus, we will continue to experience the confusion exhibited by Pritchard and Sues 2016 (above). This has been documented online for the last seven years.

References
Pritchard AC, Sues H-D 2016. Mosaic evolution of the early saurian post cranium revealed by the postcranial skeleton of Teraterpeton hrynewichorum (Archosauromorpha, Late Triassic). Abstract from the 2016 meeting of the Society of Vertebrate Paleontology.
Sues H-D 2003. An unusual new archosauromorph reptile from the Upper Triassic Wolfville Formation of Nova Scotia. Canadian. Journal of Earth Science 40(4): 635-649.

Thanks to
reader NP for bringing this taxon back to my attention.

A post-dentary reversal between rodents and multituberculates

Yesterday I promised a look at the new Jurassic gliding mammal, Arboroharamiya (Han et al. 2017), known from two crushed, but complete specimens (Figs. 1, 2). Originally this genus was considered a euharamiyid, close to the Jurassic squirrel-like Shenshou (Fig. 3) derived from trithelodont pre-mammals close to Haramiyavia.

Figure 1. The holotype specimen of Arboroharamiya HG-M017 in situ with DGS tracings added.

Figure 1. The holotype specimen of Arboroharamiya HG-M017 in situ with DGS tracings added. The skull in figure 5 comes from this specimen.

The two specimens are superficially distinct
due to the width of their extraordinary gliding membranes, reinforced with stiff fibers. I have not tested the paratype specimen in the LRT yet.

Figure 2. The paratype specimen of Arboroharamiya HG-M018, in situ. DGS color tracing added. The skull is in poor shape.

Figure 2. The paratype specimen of Arboroharamiya HG-M018, in situ. DGS color tracing added. The skull is in poor shape.

Contra Han et al. 2017
In the large reptile tree Arboroharamiya nests with Carpolestes, Ignacius, Plesiadapis, Daubentonia and Paulchaffatia, taxa excluded from Han et al. The extant rodents, Rattus and Mus, are also related and included in the Han et al. cladogram (Fig. 3).

Figure 1. From Han et al. 2017, a cladogram that nests Arboroharamiya close to Xianshou and Shenshou. Colors added to showing the shuffling of various clades in the LRT. Cyan = Eutheria. Red = Metatheria. Yellow = Prototheria. Gray = Trithelodontia. White are untested or basal cynodonts.

Figure 3. From Han et al. 2017, a cladogram that nests Arboroharamiya close to Xianshou and Shenshou. Colors added to showing the shuffling of various clades in the LRT. Cyan = Eutheria. Red = Metatheria. Yellow = Prototheria. Gray = Trithelodontia. White are untested or basal cynodonts. Silhouettes are gliders. The Allotheria is not recovered by the LRT.

Arboroharamiya provides an unprecedented look
at the post-dentary in taxa transitional between rodents + plesiadapiformes and multituberculates (Fig. 5). Earlier here, here and here multituberculates were shown to have pre-mammal post-dentary/ear bones, yet nested with placental and rodent taxa. This is a reversal or atavism, a neotonous development due to the backward shifting of the squamosal (another reversal) favoring the development of larger jaw muscles to power that uniquely shaped cutting tool, the lower last premolar. It has never been so clear as in Arboroharamiya, though.

Figure 4. Subset of the LRT nesting Arboroharamiya with Carpolestes within Rodentia

Figure 4. Subset of the LRT nesting Arboroharamiya with Carpolestes within Rodentia

Han et al. reported, “The lower jaws are in an occlusal position and the auditory bones are fully separated from the dentary.” In the new interpretation (Fig. 5) the neotonous articular is back in contact with the neotonous quadrate (both auditory bones in derived mammals) as the squamosal shifts posteriorly to its more primitive and neotonous position toward the back of the skull. Essentially the back of the skull in Arboroharamiya and multituberculates are embryonic relative to rodents.

Reversals
can be confusing because they are a form of convergence arising from neotony. The LRT separates convergent taxa by nesting them correctly with a wide suite of traits and testing them with a wide gamut of taxa.

Figure 3. Images from Han et al. Color and white labels added. Here the malleus, incus and stapes have reverted to their pre-mammal states and configurations. Note the quadrate is in contact with the articular, as in pre-mammals as the dentary and squamosal become a sliding joint, carried by larger jaw muscles. Also note the various ectotympanic bones (yellow) also present, typical of Theria.

Figure 5. Images from Han et al. Color and white labels added. Here the malleus, incus and stapes have reverted to their pre-mammal states and configurations. Note the quadrate is in contact with the articular, as in pre-mammals as the dentary and squamosal become a sliding joint, carried by larger jaw muscles. Also note the various ectotympanic bones (yellow) also present, typical of Theria.

When a few traits say: pre-mammal
and a suite of traits say: rodent descendant, go with the standard for phylogenetic analysis. Only maximum parsimony reveals reversals when they appear. If you relied on just the post-dentary traits here you’d be ‘Pulling a Larry Martin‘ and nesting Arboroharamiya with pre-mammals.

I didn’t think I’d have to
keep referring to the dear departed professor from Kansas, Dr. Larry Martin, but he did like to play that game. I’m encouraging others not to, whether they know they are doing so or not.

References
Han G, Mao F-Y, Bi-SD, Wang Y-Q and Meng J 2017. A Jurassic gliding euharamiyidan mammal with an ear of five auditory bones. Nature 551:451–457.

 

Early mammal braincase bone labels

Usually the last bones any paleontologist learns
are the names for the carpals and tarsals. That these names change with mammals makes learning them… less easy.

And then, a little later,
one comes to the lateral braincase bones (Fig. 1), which also change with mammals. Braincase bones are typically obscured by the overlying dermal bones in non-cynodont tetrapods. Often they are fused in big brained birds and mammals.

Figure 1. Braincase bones of pre-mammals and mammals from Hopson and Rougier 1993, with some (Thylacosmilus, Tupaia and Kryptobaatar) added here. Colors added.

Figure 1. Braincase bones of pre-mammals and mammals from Hopson and Rougier 1993, with some (Thylacosmilus, Tupaia and Kryptobaatar) added here. Colors added. Is the large anterior lamina of Chulsanbaatar the result of fusion? It appears so, based on sister taxa. See figure 3.

Hopson and Rougier state, “The structure of the cranial wall [in Vincelestes] does distinguish monotremes and multituberculates form all other mammals in which the braincase is adequately known.”

Unfortunately,
this statement was made without a phylogenetic analysis testing a large suite of traits. By focusing on one or a few traits these authors are “Pulling a Larry Martin“. Moreover, by providing drawings alone, the authors did not permit the possibility of a misidentification.

Braincase bones and their alternate names

  1. Anterior lamina = prootic = lamina obturans
  2. Alisphenoid = epipterygoid
  3. Periotic = fused prootic + epiotic + opisthotic

Not sure why
the single lateral braincase bone in multituberculates, like Chulsanbaatar, was labeled the anterior lamina by Hopson and Rougier, while the same bone in Didelphis and Asioryctes was labeled the alisphenoid (Fig. 1). Do these bones fuse or does one shrink and disappear?

Note that Thylacosmilus
(Fig. 1) retains both an anterior lamina and alisphenoid, just like its sister in the LRT, Vincelestes. 

Figure 3. Daubentonia skull shares a long list of traits with multituberculate skulls.

Figure 3. Daubentonia skull shares a long list of traits with multituberculate skulls.

The braincase of the platypus,
Ornithorhynchus (Fig. 1), is greatly expanded, which explains its atypical appearance.

The origin of the braincase wall
Basal Tetrapoda have an ossified braincase buried beneath their dermal cranial bones. You can readily see braincase bones in therocephalians, like Lycosuchusas the lateral temporal fenestrae grow so large they nearly contact one another at the midline over the narrow parietal.

References
Hopson JA and Rougier G 1993. Braincase structure in the oldest known skull of the therian mammal: Implications for mammalian systematics and cranial evolution. American Journal of Science 293-A-A:268–299.

A paper model of the ‘Discodactylus’ skull

Earlier a flat, but layered Adobe Photoshop plan of the skull of Discodactylus’ was presented (Fig. 1) and nested with the very similar anurognathid pterosaur, Vesperopterylus.

Figure 3. The skull of NJU-57003 reconstructed in animated layers for clarity. This is something the print media just cannot do as well. All elements are similar to those found earlier in other anurognathids.

Figure 1. The skull of NJU-57003 reconstructed in animated layers for clarity. This is something the print media just cannot do as well. All elements are similar to those found earlier in other anurognathids.

Here
a paper, paste and tape model of this plan is presented (Figs. 2, 3), made from a print out of the elements in figure 1.

Figure 1. Paper reconstruction of the Discodactylus skull and mandibles.

Figure 2. Paper reconstruction of the Discodactylus skull and mandibles. Yes, the dentary teeth don’t make sense. They are scattered in situ and this is not corrected here.

The extremely fragile skull
held together from below by slender palatal bones (maxillary palatal rods and hyoids not shown) provides a solution for a flying animal with a wide, rattlesnake-like gape.

Figure 3. Another view of the paper reconstruction of the skull and mandibles of Discodactylus.

Figure 3. Another view of the paper reconstruction of the skull and mandibles of Discodactylus.

Discodactylus megasterna (Yang et al. 2018; Middle-Late Jurassic; NJU-57003) is a complete skeleton of a disc-skull anurognathid with soft tissue related to Vesperopterylus (below). The sternal complex is quite large to match the wider than tall torso. Distinct from other anurognathids, m4.1 does not reach the elbow when folded.

This specimen was featured in a report (Yang et al. 2018) on pterosaur filaments that incorrectly aligned pterosaurs with feathered dinosaurs, rather than their true ancestors, the filamentous fenestrasaurs, Sharovipteryx and Longisquama.

Figure 4. Vesperopterylus skull reconstructed from color data traced in figure 3.

Figure 4. Vesperopterylus skull reconstructed 

Figure 2. Vesperopterylus reconstructed using original drawings which were originally traced from the photo. Manual digit 4.4 is buried beneath other bones and reemerges to give its length. Pedal digit 1 turns laterally due to metacarpal arcing and taphonomic crushing. There is nothing reversed about it. 

Figure 5. Vesperopterylus reconstructed using original drawings which were originally traced from the photo. Manual digit 4.4 is buried beneath other bones and reemerges to give its length. Pedal digit 1 turns laterally due to metacarpal arcing and taphonomic crushing. There is nothing reversed about it.

References
Yang et al. (8 co-authors) 2018. Pterosaur integumentary structures with complex feather-like branching. Nature ecology & evolution.

 

 

The clade ‘Taeniodonta’ is polyphyletic, part 1: Cimolestes

Rule #1: More taxa more precisely nest all taxa
Once again, latest Cretaceous Cimolestes goes under review, this time with many more candidate sister taxa. At present the best material for this genus is a single mandible with a complete set of teeth (Fig. 1). Rook and Hunter 2013 nest Cimolestes as the direct outgroup to the tradtional clade Taeniodonta.

According to Wikipedia,
“[Members of the genus Cimolesteswere once considered to be marsupials, then primitive placental mammals, but now are considered to be members of the order Cimolesta (which was named after the genus), outside of placental mammals proper (Rook and Hunter 2013). Before they were determined to be non-placental eutherians, the cimolestids were once considered the common ancestral group of the clades Carnivora and the extinct Creodonta.”

Figure 1. Cimolestes is represented by a toothy mandible. Here it nests with the extant Dasyurus if the back of the skull is shorter. Apparently the coronoid process is oddly narrow.

Figure 1. Cimolestes is represented by a toothy mandible. Here it nests with the extant Dasyurus if the back of the skull is shorter. Apparently the coronoid process is oddly narrow. I have not seen incisors like this in any other mammal, but Dasyurus comes close.

With so few traits to score,
Cimolestes is difficult to nest and generally causes loss of resolution, especially when other taxa data include skulls without mandibles (so, no comparable traits = loss of resolution). When deleting taxa without preservation of the mandibles the best match is with the extant marsupial, Dasyurus (Fig. 1), but with a narrower coronoid process and larger incisors, and therefore a likely shorter and smaller cranial region.

Figure 2. Traditional Taeniodonta in a cladogram. With more taxa this clade splits up according to the colors shown here.

Figure 2. Traditional Taeniodonta in a cladogram from Rook and Hunter 2013. Colors and list of body parts added here. With more taxa to be attracted to (1362 in the LRT) this clade splits up according to the three colors shown here.

Traditionally
Cimolestes is considered a basal taeniodont and all taeniodonts are considered eutherians (placentals). Other traditional taeniodonts include Protictis, Onychodectes and Stylinodon. The Rook and Hunter cladogram of eutherian relationships nests only one traditional taeniodont alongside Cimolestes (Fig. 3) and the basalmost member of the tenrec-odontocete clade (in the LRT), Maelestes.

Figure 3. The Rook and Hunter cladogram that nested traditional Taeniodonts within their Eutheria. Colors and tones added here for clarity and comparison. The LRT does not confirm most of these relationships.

Figure 3. The Rook and Hunter cladogram that nested traditional Taeniodonts within their Eutheria. Colors and tones added here for clarity and comparison. The LRT does not confirm most of these relationships.

In the large reptile tree (LRT, 1362 taxa, subset Fig. 4) none of these taxa nest with one another. Their previous joining may be due to eyeballing, a reliance on dental traits and taxon exclusion. That’s all Cope had available at the time. Modern workers appear to have followed traditional taxon lists and convergent dental traits without testing a wider gamut of taxa. The LRT includes more taxa and does not emphasize dental traits.

When tested with additional taxa,
(Fig. 4) the traditional eutherian clade Taeniodonta is polyphyletic and should be abandoned. Only a few traditional members are closely related to one another.

Figure 3. Subset of the LRT labeling several traditional taeniodonts in red, indicating the traditional clade Taeniodonta is polyphyletic and should therefore be abandoned.

Figure 3. Subset of the LRT labeling several traditional taeniodonts in red, indicating the traditional clade Taeniodonta is polyphyletic and should therefore be abandoned.

As typical,
taxa in the LRT provide and document a gradual accumulation of derived traits that competing cladograms cannot match.

More former taeniodonts to come.

References
Fox RC 2015. A revision of the Late Cretaceous–Paleocene eutherian mammal Cimolestes Marsh, 1889. Canadian Journal of Earth Sciences (advance online publication) doi: 10.1139/cjes-2015-0113.
Marsh OC 1889. Marsupialia, Cimolestidae. American Journal of Science and Arts 3d ser., XXXVIII, 89, pl. iv, figs. 8–19.
Rook DL and Hunter JP 2013. Rooting around the eutherian family tree: the origin and relations of the Taeniodonta. Journal of Mammal Evolution
DOI 10.1007/s10914-013-9230-9

wiki/Cimolestes
wiki/Taeniodonta
wiki/Cimolesta