Nesting twin-horned Arsinoitherium within the Condylarthra

Figure 1. Famous and enigmatic, Arsinoitherium has been known for over a century, and traditional paleontologists still do not know what it is.

Figure 1. Famous and enigmatic, Arsinoitherium has been known for over a century, and traditional paleontologists still do not know what it is.

FIgure 1. Subset of the large reptile tree, the Condylarthra, featuring Astrapotherium. Note the phylogenetic proximity of Astrapotherium and Tapirus.

FIgure 1. Subset of the large reptile tree, the Condylarthra, featuring Astrapotherium. Note the phylogenetic proximity of Astrapotherium and Tapirus.

Traditionally Arsinoitherium zitteli has been hard to classify.
Wikipedia reports, “Arsinoitherium (Beadnell 1902; Eocene-Oligocene, 36-30mya; 3 m in length; Fig. 1) is related to elephants, sirenians, hyraxes and the extinct desmostylians.” That’s a pretty broad gamut of taxa.

And they’re all wrong according to the large reptile tree (now 812 taxa, subset Fig. 2).

And this came as a surprise to me, too
among 811 other taxa, Arsinoitherium nests with Gobiatherium mirificum (Fig. 3; Osborn and Granger 1932; Middle Eocene), which Wikipedia considers, “one of the last uintatheres” of which Uintatherium is the titular and most famous member. Wikipedia goes on to report, “Gobiatherium lacked knob-like horns, or even fang-like tusks. Instead, it had enlarged cheekbones and an almost spherical snout. Because of the noticeable lack of many diagnostic uintathere features (the horns and tusks), the genus is placed within its own subfamily.” Here’s where tradition and the LRT agree… but let’s push this a little further to see where it takes us within the friendly confines of the current LRT taxon list.

Figure 3. Gobiatherium skull in three views. Though not immediately apparent, Gobiatherium is closest to Arsinoitherium in the LRT.

Figure 3. Gobiatherium skull (A. M. 26624) in three views. Though not immediately apparent, Gobiatherium is closest to Arsinoitherium in the LRT. Image from Osborn and Granger 1932.

Among all tested placental taxa, and despite distinct overall appearances
only Arsinoitherium and Gobiatherium:

  1. redevelop the ascending process of the premaxilla, completely enclosing the naris;
  2. produce a wide, elevated set of nasals, further expanding into horns in Arsinoitherium;
  3. only two molars, rare among placentals;
  4. and no other condylarths have a wide flat cranium, usually a crest or a convex cranium is present.

That premaxillary ascending process
looks so normal. But among marsupial and placental mammals it is very rare indeed! Of course, the LRT does not depend on one or several traits, several dozen nest Arsinoitherium with Gobiatherium and their sisters.

Even without Gobiatherium
Arsinoitherium nests with Uintatherium. Coryphodon nests closer to Uintatherium. All descend from a sister to Thomashuxleya (Fig. 4), which we’ll look at soon in greater detail.

Figure 4. Thomashuxleya is basal to uintatheries and arsionoitheres. It is not a notoungulate, an invalid taxon.

Figure 4. Thomashuxleya is basal to uintatheries and arsionoitheres. It is not a notoungulate, an invalid taxon.

We hold as an ideal
a gradual accumulation of derived traits in derived taxa, like Gobiatherium and Asinoitherium. In this clade, unfortunately we don’t have enough taxa to make that gradual accumulation of traits any more gradual than it currently is. This is the best we can do, at present, with available data and the present taxon list.

But it’s a good start!
And closer than anyone figured out before.

References
Beadnell HGC 1902. A preliminary note on Arsinoitherium zitteli, Beadnell, from the Upper Eocene strata of Egypt. Public Works Ministry, National Printing Department. Cairo: 1–4.
Lucas SG 2001. Gobiatherium (Mammalia: Dinocerata) from the Middle Eocene of Asia: Taxonomy and biochronological Significance. Paläontologische Zeitschrift 74 (4): 591–600.
Osborn HF and Granger W 1932. Coryphodonts and uintatheres from the Mongolian expedition of 1930. American Museum Novitates 552:1-16.

wiki/Arsinoitherium
wiki/Gobiatherium

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Toxodon and Pyrotherium are wombats

Earlier the LRT nested two taxa, Vintana and Zalambdalestes, with the wombat, Vombatus. I did not know then that this would start a trend among enigmatic and unusual taxa.

Today
the enigmatic South American ‘ungulates’ Toxodon (Fig. 1) and Pyrotherium (Fig. 2) move over from the decimated Notoungulata and Ungulata to nest with marsupial wombats. They lack epipubes and have only three molars (per side x4), but other related marsupials also share those traits. It’s no longer a rule that marsupials have to have four molars.

Figure 1. Toxodon was a notoungulate placental. Now it's a wombat marsupial.

Figure 1. Toxodon was a notoungulate placental. Now it’s a wombat marsupial with only three toes on each foot. Note the septomaxilla and posterior placement of the jaw glenoid.

Toxodon platensis
(Owen 1837; Pliocene-Pleistocene 2.6-.016 mya; 2.7 m in length) lost the medial and lateral toes on all four hoofed extremities. That makes it look like a perissodactyl ungulate. The high neural spines and low position of the skull remind one of North American bison. Prehistoric humans hunted them, based on the arrow tips found with skeletons.

Figure 2. Pyrotherium was another notoungulate. Now it is another wombat. From what I've seen, I think the dorsal view is fairly damaged. Note the septomaxilla (orange) and posterior placement of the jaw joint. I show the fossil and drawings because not all the parts match up.

Figure 2. Pyrotherium was another notoungulate. Now it is another wombat. From what I’ve seen, I think the dorsal view is fairly damaged. Note the septomaxilla (orange) and posterior placement of the jaw joint. I show the fossil and drawings because not all the parts match up.

Pyrotherium sorondoi
(Ameghino 1889, 1894, 1895; Early Oligocene, 29-21 mya; 3m long); data here comes only from its skull, but post-cranial pieces are known indicating a graviportal stance. Wikipedia called Pyrotherium an ungulate. Other workers (i.e. Shockley et al. 2004) had trouble nesting it, too. It converges with Arsinoitherium and elephants. Provided with a wide gamut of mammals to nest with, Pyrotherium nests with Toxodon close to Vombatus.

Figure 3. Two large wombats, Vombatus and Phascolonus for comparison.

Figure 3. Two large wombats, Vombatus and Phascolonus for comparison. These wombats have epipubes.

The wombats
are becoming much more diverse than earlier imagined. Credit ‘taxon inclusion’ for this insight and others.

References
Ameghino F 1889Contribución al conocimiento de los mamíferos fósiles de la República Argentina, obra escrita bajo los auspicios de la Academia Nacional de Ciencias de la República Argentina para presentarla a la Exposición Universal de Paris de 1889. Actas Academia de Ciencias. de Córdoba 6:11027.
Ameghino F 1894. Sur les oiseaux fossiles de Patagonie; et la faune mammalogique des couches à Pyrotherium. Boletin del Instituto Geographico Argentino 15:501-660.
Ameghino F 1895. Premiére contribution à connaissance de la fauna mammalogique de couches à Pyrotherium. Boletín Instituto Geográfico Argentino 15:603660.
Owen R 1837. Description of the cranium of the Toxodon platensis. Proceedings of the Geological Society of London 2:541-542.
Shockey BJ & Anaya F 2004. Pyrotherium macfaddeni, sp. nov. (late Oligocene, Bolivia) and the pedal morphology of pyrotheres. Journal of Vertebrate Paleontology. 24 (2): 481–488. doi:10.1671/2521.

wiki/Pyrotherium
wiki/Toxodon

New paper on stem archosauromorpha: Foth et al. 2016

When Foth et al. 2016 report,
“Here, we analyse the cranial disparity of late Permian to Early Jurassic archosauromorphs and make comparisons between non-archosaurian archosauromorphs and archosaurs (including Pseudosuchia and Ornithodira) on the basis of two-dimensional geometric morphometrics.” we are immediately ready for a bogus report based on the antiquated inclusion of the clades listed above.

Foth et al. 2016 set up their study
based on traditional phylogenies, not the large reptile tree [my comments follow]:

  1. “Living birds and crocodylians, as well as their extinct relatives including pterosaurs and non-avian dinosaurs, comprise the extraordinarily diverse and successful crown clade Archosauria.” [pterosaurs are lepidosaurs]
  2. “non-archosaurian archosauromorphs (i.e. taxa on the stem lineage leading towards archosaurs) formed a species rich component of Triassic ecosystems (>90 valid species) and achieved high morphological diversity, including highly specialized herbivores (Azendohsaurus, rhynchosaurs), large apex predators (erythrosuchids), marine predators with extremely elongated necks (tanystropheids), armoured crocodile-like forms (dosewellids, proterochampsids ), and possibly even turtles).” [Azendosaurus, rhynchosaurs, tanystropheids and turtles are all lepidosauromorphs].

The Foth et al. cladogram includes the following taxa
that have nesting problems:

  1. Tanystropheidae [should be in Tritosauria, Lepidosauria]
  2. Allokotosauria (a new paraphyletic ‘clade’ by Nesbitt et al. 2015 nesting between Protorosaurus and Prolacerta) – Pamelaria [Protorosauria], Azendohsaurus, Trilophosaurus [Rhynchocephalia]
  3. Rhynchosauria [should be in Rhynchocephalia, Lepidosauria]
  4. Pterosauria [should be in Tritosauria, Lepidosauria]
  5. and the archosauriforms could use a lot of work! It’s all mixed up in there.

The rest of the paper
discusses the large amount of  cranial disparity in this clade. No wonder there is so much cranial disparity, they have thrown in so many unrelated taxa!!! As a referee I would have sent this manuscript back to the authors. The sister taxa do not demonstrate a gradual accumulation of character traits. They really need to expand their taxon list. They are missing SO many transitional taxa.

By contrast
there is not so much cranial disparity in the archosauriform subset of the LRT because they are more closely related to each other. In fact, the differences between sisters have been minimalized by taxon inclusion, creating the microevolution between taxa that even Creationists support.

References
Foth C, Ezcurra MD, Sookias RB, Brusatte SL and Butler RJ 2016. Unappreciated diversification of stem archosaurs during the Middle Triassic predated the dominance of dinosaurs. BMC Evolutionary Biology, 2016, Volume 16, Number 1, Page 1 online here.

Nesbitt SJ, Flynn JJ, Pritchard AC, Parrish MJ, Ranivoharimanana L and Wyss AR 2015. Postcranial osteology of Azendohsaurus madagaskarensis (?Middle to Upper Triassic, Isalo Group, Madagascar) and its systematic position among stem archosaur reptiles. Bulletin of the American Museum of Natural History. 398: 1–126.

Say ‘No’ to Notoungulata. Turns out, it’s not a clade.

This is where testing takes us out on yet another limb
because the Notoungulata has been a clade for over 100 years (Roth 1903). If you are unfamiliar with this clade, as I was… you can get a basic education on the Notoungulata here,

According to
Darin Croft, PhD, Paleomammalogist, the Notoungulata is a clade of diverse South American Tertiary mammals all united, “by characters of their ear region and their teeth, including the presence of a loph on their upper molars known as the ‘crochet‘.” 

The clade Notoungulata produced taxa convergent with:

  1. buffalo/rhinos: Toxodon
  2. elephants/hippos: Pyrotherium. Astrapotherium
  3. chalicotheres: Homalodotherium
  4. peccarys: Thomashuxleya
  5. rabbits:  Protypotherium
  6. and others

Unifortunately
as I keep adding notoungulates to the large reptile tree (Fig. 1; 808 taxa at present), they keep nesting not with each other, but with a diverse selection of placental and marsupial mammals. That should not be happening, unless a false paradigm is present.

Figure 1. A selection of purported notoungulates (in amber) were added to the LRT and they did not nest together. That means they're not a clade.

Figure 1. A selection of purported notoungulates (in amber) were added to the LRT and they did not nest together. That means they’re not a clade.

Are dental characters
over-emphasized in traditional studies? including the Notoungulata? Do the cusps and valleys of molars trump the rest of the mammal’s morphology? Is it more reasonable to posit that teeth might be converging in these disparate taxa? For instance, Homalodotherium is an excellent sister to Chalicotherium, but I did not test the tooth cusps. And Toxodon is an excellent wombat. We’ll take closer looks at those taxa in future blogs.

Questioning basic assumptions is okay
because this is Science and everything is up for discussion. If a test does not deliver promised results, it’s okay to wonder why.

If we were to take the Notoungulata at face value
we would have to accept the wide range of morphologies within this one clade, as in the clade that includes tenrecs and whales. Unfortunately, testing shows that the range of body types in the Notoungulata is more readily matched by other clades, including the wombats within the marsupials and the chalicotheres within the placentals.

The loss of the clade ‘Notoungulata’
follows a list of other clades that have been lost based on the results of the LRT.

  1. Amniota is now a junior synonym for Reptilia
  2. Ornithodira is now a junior synonym for Reptilia
  3. Parareptilia is now a junior synonym for Reptilia
  4. Pterodactyloidea is paraphyletic
  5. Allotheria:  no mammals form a clade between Metatheria and Eutheria
  6. And others…

In counterpoint,
several new clades have been erected, resurrected or revised here:

  1. Archosauromorpha
  2. Lepidosauromorpha
  3. Enaliosauria = plesiosaurs + ichthyosaurs and their kin
  4. Tritosauria – a previously unrecognized squamate clade
  5. Prosquamata – another previously unrecognized squamate clade
  6. Fenestrasauria (goes back 16 years to Peters 2000, but still not used in academic publication
  7. Tenreccetacea = tenrecs + whales
  8. And several others…

Share your thoughts on this matter,
if you wish…

References
Billet G 2011. Phylogeny of the Notoungulata (Mammalia) based on cranial and dental characters. Journal of Systematic Palaeontology 9:481-497.
Cifelli RL 1993. The phylogeny of the native South American ungulates; pp. 195-216 in F. S. Szalay M J Novacek, and MC McKenna (eds.), Mammal Phylogeny: Placentals. Springer-Verlag, New York.
Roth S 1903. Los Ungulados Sudamericanos. Anales del Museo de La Plata (Sección Paleontológica). 5: 1–36. OCLC 14012855.
Scott WB 1932. Mammalia of the Santa Cruz Beds. Volume VII, Paleontology. Part III. Nature and origin of the Santa Cruz Fauna with additional notes on the Entelonychia and Astrapotheria. ; pp. 157-192 in W. B. Scott (ed.), Reports of the Princeton University Expeditions to Patagonia, 1896-1899. Princeton University, E. Schweizerbart’sche Verlagshandlung (E. Nägele), Stuttgart.

wiki/Notoungulata

Macrauchenia: a South American perissodactyl

Figure 1. Macrauchenia museum mount.

Figure 1. Macrauchenia museum mount.

Figure x. Macrauchenia cladogtam. Tapir and Chalicotherium are perissodactyls.

Figure x. Macrauchenia cladogtam. Tapir and Chalicotherium are perissodactyls.

Famous for its assumed
elephant-like proboscis, arising from a dorsal narial opening (Fig 2), Macrauchenia was a long-legged grazing ungulate with three toes on each manus and pes. In the large reptile tree it nests with Chalicotherium, which, in turn, nests with Tapirus, (the tapir) an extant perissodactyl with a short flexible trunk. A recent analysis of collagen sequences (Welker et al. 2015) found the same relationship. Not sure why this needed resolution… tapirs also have a trunk, dorsal narial opening, three hooves per foot AND some still live in South America. I guess that used to be considered ‘convergence.’ Here the LRT calls it ‘homology.’

Discovered by Charles Darwin in 1834,
and published by Richard Owen in 1836, Macrauchenia patachonica (Pliocene 7mya to Pleistocene .02mya; 3m length) was otherwise similar to a camel in proportions with a horse-like skull. Macrauchenia was an herbivore with a full arcade of short teeth in its jaws (Fig. 2). The last premolar looks like a molar, but, like other premolars, it is slightly larger than the other teeth and all sister taxa have 3 molars per side.

Figure 2. Macrauchenia skull in several view (from Owen 1836?) with bones colorized here. Note the dorsal extension of the premaxilla.

Figure 2. Macrauchenia skull in several view (from Owen 1836?) with bones colorized here. Note the dorsal extension of the premaxilla. The fossa posterior to the naris could anchor large proboscis muscles. 6 premolars and 3 molars appear to have been present. Not sure about the palatine here.

Wikpedia reports, “Macrauchenia was a long-necked and long-limbed, three-toed South American ungulate mammal, typifying the order Litopterna.  Early forms are near the condylarths, to such an extent that the litopterns might be considered merely as surviving and diversely specialized condylarths.” The LRT did not nest Macrauchenia with the basal Condylartha, but that is still a monophyletic clade that now includes all hoofed and edentate mammals — along with all the original basal condylarths.

Thanks to reader SBJ
for suggesting a number of South American mammals to add to the LRT. This is number one of several to come.

References
Owen R 1838. Description of Parts of the Skeleton of Macrauchenia patachonica. In Darwin, C. R. Fossil Mammalia Part 1 No. 1. The zoology of the voyage of H.M.S. Beagle. London: Smith Elder and Co.
Welker F et al. 2015. Ancient proteins resolve the evolutionary history of Darwin’s South American ungulates. Nature. doi:10.1038/nature14249. ISSN 0028-0836.
wiki/Macrauchenia

Is this the footprint of Arizonasaurus?

Figure 1. Synaptichnium MNA V3425. Arrow points to direction of movement and aligns with sagittal plane. PILs and pads added.

Figure 1. Synaptichnium MNA V3425. Arrow points to direction of movement and aligns with sagittal plane. PILs and pads added. The pink manus track is another specimen.

The middle Triassic Moenkopi formation
in Arizona has provided a rich trove of fossils. An excellent footprint (MNA V3425, Fig. 1) was recently published online here and attributed to Arizonasaurus, a likely bipedal carnivorous archosauriform (Fig. 2). Arizonasaurus was derived from basal Rauisuchia, like Vjushkovia, and is most closely related to Yarasuchus and Qianosuchus according to the large reptile tree.

Figure 2. Arizonasaurus. Not sure which of the two mandibles is correct here, so both are presented. Note, neither manus nor pes is preserved in the specimen.

Figure 2. Arizonasaurus. Not sure which of the two mandibles is correct here, so both are presented. Note, neither manus nor pes is preserved in the specimen.

According to the online article,
“Paleontologist Christa Sadler has written a book, “Dawn of the Dinosaurs,” about the archosaurs of the Middle and Late Triassic in the region. Unusually detailed footprints of the large reptile, or something like it, are preserved in a slab of Moenkopi sandstone in the collections repository at the Museum of Northern Arizona, where Sadler has studied. MNA  [Museum of Northern Arizona] Colbert Collections Curator of Vertebrate Paleontology David Gillette, Ph.D., says the footprints were discovered in Wupatki National Monument in 1973.”

Figure 3. Manus impression of man v3245. Note the heavy scales here.

Figure 3. Manus impression of man v3245. Note the heavy scales here.

The LRT currently doesn’t include ichnites (footprints)
but let’s see what happens this time, since the track is so precisely imprinted. Unfortunately, Arizonasaurus does not preserve the manus or the pes (Fig. 1). Nevertheless, out of 801 candidate taxa, MNA 3425 nests with a sister to Arizonasaurus, Decuriasuchus, and is similar to the pes of other Arizonasaurus sisters, Qianosuchus and Nandasuchus, all Middle Triassic taxa. So, phylogenetic bracketing works, at least to this extent. And it just shows you don’t need a long list of character traits to successfully nest some taxa.

Figure 3. Scaly palms of two crocodilians. Digit 1 is on the left in both specimens.

Figure 4. Scaly palms of two crocodilians. Digit 1 is on the left in both specimens.

Notes on the scaly palm of MNA V3425
Dinosaur footprints do not have large scale impressions. By contrast, croc hands and feet do have large scales (Fig 3). The sisters to Arizonasaurus, Qianosuchus and Yarasuchus, both have short limbs, a long rostrum and a general crocodile-like build. Likewise Decuriasuchus was long-bodied, quadrupedal with a large foot and a presumably small hand (not preserved). In similar fashion, Arizonasaurus likely also had a large foot and small hand based on its pectoral and pelvic girdles and femur (Fig. 2), but was a likely biped.

Figure 5. Decuriasuchus does not preserve the manus, but it was probably small based on the forelimb.

Figure 5. Decuriasuchus does not preserve the manus, but it was probably small based on the forelimb.

Belated apologies
to those who tried [or continue to try] to access www.reptileevolution.com yesterday and today. Eviidently the server is down, wherever it is. I can’t access it either to make updates and repairs. Hopefully the RepEvo website will be restored soon. :  )

 

Peltephilus, the horned armadillo, alas, is not an armadillo

Peltephilus ferox is yet another armadillo-mimic. Close to armadillos… but not one.

Figure 1. Peltephilus skull, manus and pes. Note the lack of a palate exposure of the premaxilla, with the canines moving to an anteromedial position formerly occupied by incisors. Otherwise there are 3 premolars and 3 molars present, the standard pattern for sister taxa. Real armadillos have long, narrow rostra with an elongate premaxilla and 7 cone-shaped identical teeth none of which extend below the orbit.  Two species / specimens are shown here.

Figure 1. Peltephilus skull, manus and pes. Note the lack of a palate exposure of the premaxilla, with the canines moving to an anteromedial position formerly occupied by incisors. Otherwise there are 3 premolars and 3 molars present, the standard pattern for sister taxa. Real armadillos have long, narrow rostra with an elongate premaxilla and 7 cone-shaped identical teeth none of which extend below the orbit.  Two species / specimens are shown here. Line art is from Vizcaino and Farina 1997,

In the LRT
Peltephilus (Fig. 1) nests between Glyptotherium (not an armadillo) and Bradypus (a sloth) – but that’s not even the big story (see below) with this highly derived, armored herbivore.

Figure 4. Skull of the armadillo Dasypus from Digimorph.org, used with permission. and select bones colorized.

Figure 2. Skull of the armadillo Dasypus from Digimorph.org, used with permission. and select bones colorized. Real armadillos have long, narrow rostra with an elongate premaxilla and 7 cone-shaped identical teeth none of which extend below the orbit.

According to
Wkiipedia, “Peltephilus ferox (Ameghino 1887‭; 1.5 m long) the horned armadillo, is an extinct species of dog-sized, armadillo xenarthran mammal which first inhabited Argentina during the Oligocene epoch, and became extinct in the Miocene epoch. Notably, the scutes on its head were so developed that they formed horns protecting its eyes. Aside from the horned gophers of North America, it is the only known fossorial horned mammal. Although it had traditionally been perceived as a carnivore because of its large, triangular-shaped teeth, Vizcaino and Farina argued in 1997 that Peltephilus was a herbivore.”

Figure 3. Subset of the large reptile tree showing the nesting of Barylambda with Orycteropus and Xenarthra.

Figure 3. Subset of the large reptile tree showing the nesting of Peltephilus between Glyptotherium and Bradypus.

Postcranially
Peltephilus had transverse bands of ossified armor along the back. It had short legs and large claws, ideal for digging or ripping open ant colonies.

The teeth are the story here
The seven teeth (x4) of Peltephilus formed a complete arcade. They were all similar in shape. Apparently (based on the above data), like the similarly short-faced Bradypus, the reduced premaxilla did not extend to the palate. No edentates have premaxillary teeth. In Bradypus the lost premaxilla leaves a space between the anterior maxillae. By contrast, in Peltephilus the maxillae join in medial contact. With that medial migration the canine teeth also migrate medially, taking the place of the absent incisors. The remaining 3 premolars and 3 molars comprise the remainder of the arcade with the molars remaining ventral to the laterally expanded jugals, as in sister taxa.

Figure 2. Bradypus skull from Digimorph.org, used with permission, colors added to select bones.

Figure 42. Bradypus skull from Digimorph.org, used with permission, colors added to select bones.

Phylogenetic bracketing
confirms the hypothesis of Vizcaino and Farina 1997 that Peltephilus was also an herbivore, not a vicious carnivore as Ameghino 1894 envisioned. Vizcaino and Farina list the following differences with Dasypodidae (Dasypus). Note how many traits here are shared with Bradypus and Glyptotherium [marked with a green dot ]

  1. Short and broad rostrum
  2. Wide nasal (narial) openings 
  3. Short jaw 
  4. Completely fused and expanded mandibular symphysis  
  5. Low condyle  
  6. Teeth with chisel-like occlusal surfaces  
  7. U-shaped tooth row  
  8. Horn-bearing cephalic (head) shield

References
Ameghino F 1894. Enumeration Synoptique des especes de mammiferes fossiles des formations Eocenes de Patagonie. Boletin de la Academia Nacional de Ciencias en Cordoba (Republica Argentina) 13:259-452
Ameghino F 1897. Mamiferos Cretaceos de la Argentina. Segunda contribucion al conocimiento de la fauna mastologica de las capas con restos de Pyrotherium. – Boletin Instituto Geografico Argentino 18:406-521.
Vizcaino SF and  Farina RA 1997. Diet and locomotion of the armadillo Peltephilus: a new view. Lethaia, 30, 79-86.

wiki/Peltephilus