Insectivores and Rodents (including a Multituberculate) added to the LRT

Today several Insectivores (clade within the Mammalia)
and other taxa are added to the large reptile tree (now 744 taxa). And, no surprise, the little fur-balls nest together (subset Fig. 1). Talpa is a mole. Scutisorex is a shrew. Solenodon is, well, a solenodon!

Figure 1. the mammal subset of the large reptile tree, still fully resolved. Here insectivores nest with rodents and rabbits. Plesiadapis is often traditionally nested with primates in analyses performed by others, but does not do so here.

Figure 1. The mammal subset of the large reptile tree, still fully resolved. Here insectivores nest with rodents and rabbits. Plesiadapis is often traditionally nested with primates in analyses performed by others, but does not do so here. If some of these taxa are unfamiliar, you can Google them to retrieve their more familiar names. It’s a pretty simple tree. And, doggone it, it makes sense, too!

As you can see,
Tenrecs are no longer insectivores. Insectivores are sisters to Solenodon and that clade is a sister to the rodents + Rugosodon (Jurassic, Yuan et al. 2013), a multiuberculate mammal. Rugosodon is the oldest multituberculate so far described, so it should be one of the least derived. They have flexible ankles, according to Wikipedia.

About multituberculates
Wikipedia reports, “Multituberculates are extinct rodent-like mammals usually placed outside either of the two main groups of living mammals—Theria, including placentals and marsupials, and Monotremata[9]—but closer to Theria than to monotremes. (references on that page). Sorry to report this, but after testing in the large reptile tree, multituberculates appear to be rodent-like because they are rodent sisters. If you have any suggestions for taxa that might attract Rugosodon away from rodents, toward the base of the Mammalia, please pass them on.

A few carnivores were added.
Phoca is a seal. Procyon is a raccoon (and a bright star).

If you want to check my work
I’ll have images and pages set up at ReptileEvolution.com after the upcoming weekend. Otherwise, nearly all the images I used for data were Googled. So you can find the same data online.

References
Yuan CX, Ji Q, Meng QJ, Tabrum AR, Luo ZX 2013. Earliest evolution of multituberculate mammals revealed by a new Jurassic fossil”. Science 341 (6147): 779–783. doi:10.1126/science.1237970.

 

Mesonyx: hippo sister, baleen whale ancestor

Since this post, about 500 taxa have been added to the LRT. Some of them split odontocetes + tenrecs from mysticetes + mesonychids (through hippos and desmostylians).

The wolf-sized mammal,
Mesonyx uintensis (Cope 1872; Late Eocene, 50mya; 42 cm cranium length) looks like a hooved predator, and maybe it was. But Mesonyx nests between herbivores and those big canines are also found in its sister, Hippopotamus, according to results recovered from the large reptile tree (740 taxa and growing).

Figure 1. Mesonyx, the first known mesonychid was a sister to Hippopotamus in the large reptile tree. So maybe it was a plant eater.

Figure 1. Mesonyx, the first known mesonychid was a sister to Hippopotamus in the large reptile tree. So maybe it was a plant eater.

Mesonyx was a mesonychid and an even-toed ungulate (artiodactyl).
Andrewsarchus, traditionally considered a giant mesonychid, is not related, as we learned earlier (contra Osborn 1924). The legend of Andrewsarchus and its purported relationship to Mesonyx is where the whale/artiodactyl hypothesis had its origin. Analysis has invalidated that hypothesis (contra Spaulding et all 2009), but supports the odontocete /tenrec hypothesis of which Andrewsarchus remains a part as a giant tenrec.

I hope you’re concerned about the state of
systematics within vertebrate paleontology at present. In 2016 there should not be this many problems with traditional tree topologies and individual taxa. If an amateur working from unfamiliar online images is able to piece together a tenable topology of reptile (plus mammal and bird) relationships different from and more logical than traditional topologies, then there’s a problem out there. Students put their faith in what they read in textbooks. They get better grades when they are able to repeat what they’ve read. Manuscripts get approved if they follow dogma. As scientists, however, we need to test assertions, especially those hypotheses of relationships that many agree are flimsy.

References
Osborn HF 1924. Andrewsarchus, giant mesonychid of Mongolia. American Museum Noviattes 146: 1-5.
Spaulding M, O’Leary MA, Gatesy J 2009. Relationships of Cetacea (Artiodactyla) Among Mammals: Increased Taxon Sampling Alters Interpretations of Key Fossils and Character Evolution. PLoS ONE 4(9): e7062. doi:10.1371/journal.pone.0007062

 

Andrewsarchus: another giant elephant shrew close to tenrecs.

“This is the largest terrestrial carnivore which has thus far been discovered in any part of the world.” — Henrey Fairfield Osborn 1924

After this blog was written more taxa (almost a thousand, I now see, not all relevant to this discussion) slightly shifted Andrewsarchus to the next node over: elephant shrews and leptictids along with Sinonyx.

Figure 1. Andrewsarchus. Only the giant skull is known. This is a giant tenrec,another land-based pre-whale.

Figure 1. Andrewsarchus. Only the giant skull is known. This is a giant tenrec,another land-based pre-whale.

Wikipedia, representing traditional paleontology,
describes Andrewsarchus (middle Eocene, Fig. 1) as an extinct mammal, generally classified as a mesonychid, but recent discoveries recover it as an artiodactyl closely related to entelodonts (hell pigs). hippos and whales.

The present phylogenetic analysis 
(Fig. 2) documented at the large reptile tree (now 238 taxa), recovers Andrewsarchus in the tenrec / whale clade along with tenrecs we looked at earlier here and here. It doesn’t look like an artiodactyl because it isn’t one. I’ll have to test Mesonyx to see if mesonychids are tenrecs or not. At this point, all the taxa have a rather long rostrum and not much in the way of canines.

Spaulding et al. 2009
integrated molecules and fossils to provide “the most robust test of the phylogeny of cetaceans. We do this in the context of the largest total evidence analysis of morphological and molecular information for Artiodactyla (661 phenotypic characters and 46,587 molecular characters, coded for 33 extant and 48 extinct taxa).” They considered Andrewsarchus, “a relatively incomplete fossil from Mongolia that has been historically difficult to classify.”

Unfortunately
cetaceans are not artiodactyls. So, like workers who add pterosaurs to archosaur studies, Spaulding et al. were barking up the wrong tree. With far less data and no first hand exposure the large reptile tree was able to find the real ancestors of whales simply by employing a wider gamut of taxa. On the face of it, whales don’t belong with mammals that were reducing their toes to just a few hooves and reducing their tails to something that barely covered their anus. They are much better nested with mammals with long flat feet and long tails, like the tenrecs.

The clade proposed by Spaulding et al.,
Cetancodonta (whales + hippopotami’s) to replace Whippomorpha (whales + hippopotami’s) are both invalid according to the present results.

The post-crania of Andrewsarchus
can be more accurately guessed at based on phylogenetic nesting between Leptictis and Hemicentetes: a deep chest, supple lumbar region, long flat feet and a short neck. The tail might be long and slender or short, like that of a bear.

Etc.
After tracing the skull bones of Dusisiren for addition to the taxon list, I realized that likewise in elephants the nasals were separated by an anterior process of the frontals and  that illustration was changed here.  Several other taxa were added to the mammal subset of the large reptile tree.

References
Osborn HF 1924. Andrewsarchus, giant mesonychid of Mongolia. American Museum Noviattes 146: 1-5.
Spaulding M, O’Leary MA, Gatesy J 2009. Relationships of Cetacea (Artiodactyla) Among Mammals: Increased Taxon Sampling Alters Interpretations of Key Fossils and Character Evolution. PLoS ONE 4(9): e7062. doi:10.1371/journal.pone.0007062

How whales started swimming (new players, new hypothesis)

Earlier
here and here we looked at the whale-tenrec connection.

Figure 1. Maiacetus is a basal whale with legs and it is also a giant tenrec. Compare to Hemicentes in figure 2 and remember that another tenrec, Limnogale, has a long tail.

Figure 1. Maiacetus is a basal whale with legs and it is also a giant tenrec. Compare to Leptictidium in figure 2. Hind limbs are shown in running pose. Both go back while swimming.

Spoiler alert:
Pre-whales, like Maiacetus (Fig. 1), started swimming by converting terrestrial bipedal hopping, as in Leptictidum, (Figs. 1,2) to simultaneous hind limb paddling which promoted lumbar flexion and extension with the large tail snaking up and down in waves as in living whales. Here’s how it happened in a bit more detail:

Figure 1. Leptictidium is known as a hopper. Here it nests with whales. Combine the two and when Lepticitidium jumps in the water, it continues hopping. That long, long tail is homologous to the long, long tail in Zeuglodon.

Figure 2. Little Leptictidium is widely considered a terrestrial hopper, like a kangaroo. Here it nests with whales. Combine the two and put Lepticitidium  in water, it continues hopping.

  1. Leptictidium was a bipedal tenrec that nests as a sister to land (stem) whales and aquatic whales (Fig.3).
  2. On land, Leptictidium might have hopped, like a kangaroo. Or maybe not.
  3. In water, Leptictidium let its legs extend backward as it undulated its supple spine and greatly elongated robust tail (Fig 1) in the manner of sea otter (see video). Of course all four legs contributed to propulsion and steering.
  4. Over time, the longer tail and lumbar region became more efficient, reducing the need for drag-inducing hind legs. The pelvic connection was already loose at this stage. So were the leg joints.
  5. Leptictidium was preserved with a complete pelage of thick fur. That disappears, of course, in whales.
Figure 2. Elements of Leptictidium nasutum SMF ME 1143 from Storch and Lister 1985 (labeled L. auderiense at Wikipedia). Head + torso = 30cm.

Figure 3. Elements of Leptictidium nasutum SMF ME 1143 from Storch and Lister 1985 (labeled L. auderiense at Wikipedia). Head + torso = 30cm.

Current and traditional thinking from Wikipedia: 
“Leptictidium (Early Eocene, 50 mya) is on a short list of bipedal mammals. Combination of primitive eutherian traits (prepubic bones) with derived adaptations such as the powerful hind limbs and long tail. Adapted to a forest ecosystem, Leptictidium is considered omnivorous and its lineage became extinct 35 mya. 

“The ankles and the sacroiliac joint were quite loosely fixed, while the pelvis had a flexible joint with only one coccygeal vertebra. The anteorbital muscle fenestrae in their crania suggest they probably had a long and mobile snout, similar to that of elephant shrews.  Its dentition was quite small in comparison to the size of the mandible and the animal as a whole.

“Studies of the bone structure of Leptictidium have yielded contradicting information: its leg articulations appear too weak to have supported the shock of repeated jumps, but its long feet were obviously adapted for jumping rather than running.”

That extinction statement is not exactly true
as both tenrecs and whales continue this lineage, though neither are bipedal nor do they have such proportions anymore. But this is news that the Wiki writer was not aware of.

It’s interesting and supportive of the present hypothesis
that the leg, ankle and hip joints of Leptictidium are considered “loose”. On whales, of course, the sacral connection to the pelvis is long gone. The Messel pit, from which several fossils were found, was a former lake. Maybe Leptictidium was not a hopper, but a swimmer. The long flexible snout hypothesized for Leptictidium could have been used as a snorkel to keep it underwater while breathing. And so, this is likely the origin of the cetacean blow hole.

Traditional renderings of whale swimming origins
usually employ a wolf-sized predator at the water’s edge. Now we can reduce that to a rabbit-size or smaller predator/insectivore.

If you still like hippos for whale ancestors 
as DNA, prior morphological studies and several helpful paleontologists suggest, with hippos (or the earlier ungulate Elomeryx) you don’t get a long supple lumbar area, a long tail, long flat feet with long toes, a long narrow snout with small triangular teeth or really anything else whales are famous for, except, perhaps, blubber.

This heretical discovery
should be seen as one more nail in the coffin of DNA studies that try to draw cladograms from their unsupportable results. We’ve seen similar untenable cladograms nesting turtles as archosaurs and glyptodonts as armadillos.  It’s time to put our thinking caps on and see hard evidence for what it is. Only morphological studies, and good ones, will recover gradual accumulations of derived taxa. Put all such studies under the magnifying glass to see if they make sense. Let’s put DNA studies on the shelf until they produce results that confirm morphological studies.

Figure 5. Mammal cladogram with tenrecs and stem whales highlighted. At present, Leptictidium is the closest outgroup to stem whales.

Figure 3. Mammal cladogram with tenrecs and stem whales highlighted. At present, Leptictidium is the closest outgroup to stem whales, represented here by Maiacetus.

This hypothesis could not have been recovered 
without the data and skeletons provided by Phillip Gingerich, Hans Thewissen and other stem whale discoverers over the last few decades. Phylogenetic analysis based on morphological data permitted seeing Leptictdium in a new light, as a swimmer, not a hopper with loose joints.

References
Storch G and Lister AM 1985. Leptictidium nasutum, ein Pseudorhyncocyonide aus dem Eozän der “Grube Messel” bei Darmstadt (Mammalia, Proteutheria). Senckenbergiana lethaea 56:1-37.

wiki/Pakicetus
Whale video 1
Whale video 2
Whale video 3

 

Two more little whale ancestors

Updated Sept 04, 2016, replacing Onychodectes with Anagale as the taxon list increases.

More heresy
Earlier the tiny tenrec, Hemicentetes, nested with wolf-sized Maiacetus, the land whale in the large reptile tree (731 taxa). Back then I promised to add Hippopotamus to the tree and I do so today. Among several other mammals, I also add two more that surprisingly happen to nest on the whale line, Leptictis and Anagale (Fig. 1).

Figure 1. Whale ancestor skulls. Here Anagale,, Leptictis, Hemicentetes and Maiacetus demonstrate a gradual evolution of traits that cannot be improved by the traditional whale ancestor outgroup, Hippopotamus.

These nestings
(Fig. 2) are heretical. But they demonstrate a gradual accumulation of traits that the traditional and/or current best whale ancestor outgroup candidate Hippopotamus cannot match. DNA studies evidently send us down blind allies when it comes to distantly related taxa.

The tree topology has not changed yet
despite the many additions to the cladogram, both extinct and extant. A multituberculate, Rugosodon, and an apatemyid, Apatemys have been added. We’ll take a look at those and others soon.

I’m learning as I go
and learning that this tree does not match any prior and larger attempts at mapping mammal phylogeny. That’s too bad. It’s always better to confirm prior work. There will come a day when I will either recover a rearranged tree or I will be critical of prior work. In either case, there will be a reason why. At present all the puzzle pieces fit pretty well.

Tomorrow
yet another surprising whale ancestor puts a new twist on how cetacean swimming originated.

Mammal phylogeny employing fossil and extant taxa

Current hypotheses of relationships among mammals
may cause one to develop a large cartoon question mark over one’s cranium. Traditional paleontologists still cannot recover the closest sisters to bats and they continue to suggest that hippos are the closest sisters to known pre-whales with legs.

Unfortunately
very few fossil taxa are employed in these analyses (send them along if you know of any). DNA studies don’t completely match morphological studies and they ignore fossil taxa. Wikipedia sums up the current thinking dividing paleontologists from molecular biologists.

Molecular Biologists recover this tree (highly simplified):

  1. Atlantogenata =
    Xenartha (sloth + anteater + armadillo)
    Afrotheria (golden mole + elephant shrew + tenrec + aardvark + hyrax + elephant + sea cow) Afroinsectiphilia (golden mole + elephant shrew + tenrec),
  2. Boreoeutheria (Boreotheria) =
    Euarchontoglires (rodent +  rabbit + tree shrew + flying lemur + primate + Plesiadapis)
    Laurasiatheria (hedge hog + mole + shrew + bat + pangolin + carnivores + odd-toed ungulates + even toed ungulates + whales)

Traditional paleontologists recover this tree (highly simplified):

  1. Xenarthra (sloth + anteater + armadillo)
  2. Afrotheria (hyrax + elephant + sea cow)
  3. Boreoeutheria (Boreotheria) =
    Euarchontoglires (rodent +  rabbit + tree shrew + elephant shrews + flying lemur + primate + Plesiadapis)
    Laurasiatheria (hedge hog + mole + shrew + bat + pangolin + carnivores + odd-toed ungulates & aardvark + even toed ungulates & whales)

So there is broad agreement between the two camps.
The problem comes when one tries to replicate the experiment (Fig. 1). Adding mammal taxa to the large reptile tree delivers a different hypothesis of relationships. It preserves some traditional relationships and recovers some new ones. If you’re not sure why this keeps happening here, it happens on the professional level, too. Some prior workers employ suprageneric taxa. Others do not employ fossil taxa. I also wonder if there is substantial convergence in the dental traits of included taxa. Teeth vary greatly within the Mammalia.

The ReptileEvolution.com tree (built taxon by taxon)
presented here (Fig. 1) seems to make more sense (more sister taxa look similar to one another) with a basal split between large arboreal omnivores (that ultimately produced carnivores) and small arboreal omnivores (that ultimately produced large and small herbivores and some insectivores).

Figure 1. The family tree (cladogram) of mammal interrelationships. Here the basal division is between carnivores and insectivores + herbivores.

Figure 1. The family tree (cladogram) of mammal interrelationships. Here the basal division is between slightly larger arboreal omnivores and slightly smaller arboreal omnivores. Of course, evolution kicks into high gear once  the dinosaurs are gone.

Similarities with traditional trees:

  1. Outgroups include cynodonts, monotremes and marsupials in that order.
  2. Eomaia is a basal placental (eutherian) despite retaining prepubic bones.
  3. Primates nest together and with a flying lemur
  4. Bats nest with carnivores
  5. Civets nest together
  6. Rodents nest with rabbits and one tree shrew
  7. Xenarthans nest together
  8. Ungulates nest together with Phenacodus (55 mya) at their base
  9. Elephant nests with hyrax

Differences with traditional trees:

  1. There are no geography-based divisions here, only morphology
  2. The basic division is between arboreal civet-like omnivores and arboreal rodent-like omnivores.
  3. Pangolin nests with primates and Plesiadapis does not
  4. Tree shrews are not a single clade. Tupaia nests with rodents, rabbits and Plesiadapis. Ptilocercus nests with flying lemur.
  5. Bats nest with a specific carnivore: Chriacus.
  6. Whales nest with tenrecs and pre-tenrecs, not ungulates
  7. Aardvark nests with armadillo derived from Pantolambda, which has a carnivore-like appearance).
  8. Ungulates nest with elephant + hyrax all derived from a sister to Phenacodus.

In the large reptile tree, all sister taxa share a long list of traits
and look similar to one another. You can’t say that about competing hypotheses which don’t always include fossil taxa. The mammals subset of the large reptile tree (725 taxa) has grown so far without tree topology changes. Taxa just drop in between existing nodes.

Very few tooth characters are used here.
And none distinguish one post-canine tooth from another other than [absent, blunt, sharp, multi cusp and multi cusp with constricted base] and another trait notes where the posterior maxillary tooth erupts relative to the orbit.

Wikipedia suggests that:
“Paleontologists naturally insist that fossil evidence must take priority over deductions from samples of the DNA of modern animals. More surprisingly, these new family trees have been criticised by other molecular phylogeneticists, sometimes quite harshly.”

We’ve come a long way…
Simpson 1945 was able to list several subclasses and orders, but was unable to show interrelationships. Novacek 1992 discussed several problems right before computer-assisted phylogenetic analysis came along.

Suggestions for pertinent mammal taxa that need to be added to the LRT?
Please, send them along.

References
Novacek MJ 1992. Mammalian phylogeny: shaking the tree. Nature Review Article. 356:121-125.
Simpson GG 1945. The principles of classification and a classification of mammals. Bulletin of the AMNH Bulletin of the American Museum of Natural History 85:1-350. online.
Songa S, Liub L, Edwards SW and Wub S 2012. Resolving conflict in eutherian mammal phylogeny using phylogenomics and the multi species coalescent model. PNAS 109 (37): 14942-14947.
Spaulding M, O’Leary MA and Gatesy, J 2009.
Relationships of Cetacea (Artiodactyla) among mammals: Increased taxon sampling alters interpretations of key fossils and character evolution. PLoS ONE 4:e7062. doi:10.1371/journal.pone.0007062:1-14.

why evolution is true – mammal tree

 

 

Feathered T-rex video: Excellent!*

The best video* I’ve seen on feathered dinosaurs.
*But note: their gliding Anchiornis forgot how to flap. Flapping came first. Then flapping with bipedal climbing. Then flapping with flying. Birds don’t come by gliding except to rest while airborne. Same with bats (if any glide ever). Same with pterosaurs. Let’s take gliding out of the equation for the origin of flight. That’s widespread antiquated thinking not supported by evidence. If you glide you do not flap. If you flap, some of your ancestors may learn to glide.

Click here or on the image to play.

Glyptodonts: Armored sloths, not giant armadillos.

Today three taxa were added
to the large reptile tree (now 720 taxa, subset Fig. 1):

  1. Bradypus (three-toed sloth)
  2. Dasypus (armadillo)
  3. Glyptotherium (glyptodont)

Wikipedia reports, “Glyptodonts are an extinct subfamily of large, heavily armored armadillos. Unfortunately, Glyptotherium the glyptodont nests with Bradypus, the sloth in the large reptile tree – and, as you’ll see… for good reason.

Figure 1. Mammals with a few edentates added. Here glyptodonts nest with sloths, rather than armadillos, contra traditional studies.

Figure 1. Mammals with a few xenarthans added. Here glyptodonts nest with sloths, rather than armadillos, contra traditional studies.

Bradypus is the long-legged arboreal tree-hanging sloth
with fewer toes. Just imagine where the short-legged ground sloth will nest. This hypothesis of edentate relationships runs counter to tradition, but one look at the skulls (Figs. 1, 2) and you’ll wonder why this hasn’t been noticed before.

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

Figure 2. Bradypus skull from Digimorph.org, used with permission, colors added to select bones. Compare to the glyptodont skull in figure 3. Darker images bring out lighter details.

Both the sloth and the glyptodont
have deep, narrow, flat-topped skulls with a deep ventral process of the jugal and a very short rostrum. These traits, along with a long list of others, split armadillos + aardvarks from sloths + glyptodonts.

Figure 3. Glyptodon skull with select bones colorized. Compare to the sloth in figure 2 and the armadillo in figure 4.

Figure 3. Glyptodon skull with select bones colorized. Compare to the sloth in figure 2 and the armadillo in figure 4.

Here armadillos nest with
aardvarks, like Orycteropus, a clade that was once accepted under the clade Xenartha. According to Wikipedia, xenarthans have extra vertebral articulations, the lowest metabolic rates among therians, the ischium and sacrum are fused and males have internal testicles. Pangolins were once considered xenarthans, but here nest with basal primates.

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

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

 

Note the nesting of 
whales (Maiacetus) + tenrecs (Hemicentetes), another clade without external testicles. As a scientist, I’m pleased to discover these interrelationships, but a little surprised that no one has seen this before. If you that has happened already, I will be glad to promote those papers here.

Placental mammals
are showing a basal split between carnivores and other insectivore / herbivore placentals (eutherians).

 

Uintatherium nests with the ungulates in the LRT

At present,
the large reptile tree (LRT) has been growing for five years. In all that time the tree topology has not exchanged branches very often. Instead it continue to grow like a real tree, adding leaves between existing branches and nodes.

Adding mammals comes with a new set of risks
because mammals are often identified by their teeth. The LRT does not include mammal tooth traits, so mammals are nested by the same traits as other reptiles here.

Figure 6. Uintatherium overall. Note the postcranial similarities with Arsinoitherium.

Figure 1. Uintatherium overall.

The latest additions include
the traditional condylarths, Phenacodus and Uintatherium, along with the pantodont, Alcidedorbignya (Fig.1). It may be by convergence, or it may be an echo of actual evolutionary events, but Phenacodus nests at the bnase of the present list of herbivores, including ungulates and elephant (Elephas) + hyrax (Procavia). The aardvark (Orycteropus) is the proximal outgroup. Uintatherium nests at the base of the ungulates, like a robust five-toed deer. Uintatherium also has the short toes of an elephant.

Figure 2. Uintatherium skull with bones tentatively identified. I have found no data online to support or refute these tracings. Note the shifting of the mandible to the invivo position, where the jaw joint is correct and the teeth are better aligned. The premaxilla appears to extend like a laminate over the maxilla.

Figure 2. Uintatherium skull with bones tentatively identified. I have found no data online to support or refute these tracings. Note the shifting of the mandible to the invivo position, where the jaw joint is correct and the teeth are better aligned. The premaxilla appears to extend like a laminate over the maxilla.

 

I wonder
if mammal phylogeny is more simple that traditionally portrayed? The nesting of Uintatherium with fanged deer and fangless giraffes and derived from a sister to Phenacodus is not a fluke. There are very few traits in Uintatherium that do not appear in these closest relatives.

Likewise
the pantodont, Alcidedorbignya, nests at the base of PantolambdaEctoconus. In addition to teeth, the pattern of arterial and nerve openings in the skull are used in traditional cladograms, along with other details on other bones.

Wikipedia considers pantodonts to be herbivores. However de Muizon et al. 2015 report that “Pantodonts are generally large-sized herbivorous to omnivorous mammals from the Palaeogene, Pantodonts are traditionally diagnosed by a distinctive dental synapomorphy, the double V-shaped morphology of the upper premolars, a character that has not been observed so far in other eutherians.”

de Muizon et al. note that their Alcidedorbignya dates from 65 mya, just after the asteroid collision. “It was a moderately agile, plantigrade, generalized terrestrial mammal with good climbing ability (scansorial) and occasionally capable of standing in a bipedal position. The scutiform ungual phalanges were probably bearing nail-like hooves (or primate-like nails) and because of the absence of claws, fossorial habits are unlikely.”

Figure 3. Alcidedorbignya skull about full scale at 72 dpi screen resolution. Select bones are colorized.

Figure 3. Alcidedorbignya skull about full scale at 72 dpi screen resolution. Select bones are colorized.

de Muizon et al
did a fantastic job of extricating, describing and reassembling Alcidedorbignya. They perfumed CT scans, traced vein paths and performed a large gamut phylogenetic analysis that the large reptile tree cannot, at present, compete with.

Figure 5. Alcidedorbignya bones remarkably complete for the Paleocene, 65 mya and remarkable prepared.

Figure 5. Alcidedorbignya bones remarkably complete for the Paleocene, 65 mya and remarkable prepared. Scale bar is 2 cm or about half the in vivo size. This is a small pantodont.

References
Muizon C de, Billet G, Argot C, Ladevèze S & Goussard F 2015. Alcidedorbignya inopinata, a basal pantodont (Placentalia, Mammalia) from the early Palaeocene of Bolivia: anatomy, phylogeny and palaeobiology. Geodiversitas 37 (4): 397-634.

 

A living whale ancestor you can hold in the palm of your hand

I was as surprised to see this develop, as I’m sure you will be.
Adding the land whale Maiacetus inuus (Gingerich et al. 2009, Eocene ~47 mya, 2.6 m in length; Fig. 1) to the large reptile tree (Fig. 3) nested it at the base of the current Afrothere/herbivore clade along with the tenrec, Hemicentetes (Fig. 2). The resemblance is remarkable, despite the difference in size. And this sets the earliest origin of whales on a slightly different tangent with, I’m sure you’ll agree, much better support.

Figure 1. Maiacetus is a basal whale with legs and it is also a giant tenrec. Compare to Hemicentes in figure 2 and remember that another tenrec, Limnogale, has a long tail.

Figure 1. Maiacetus is a basal whale with legs and it is also a giant tenrec. Compare to Hemicentes in figure 2 and remember that another tenrec, Limnogale, has a long tail, webbed feet and a semiaquatic niche.

Tenrecs have been traditionally associated with
a list of mammals of African origin: golden moleselephant shrews,  aardvarks (Orycteropus), hyraxes (Procavia), elephants (Elephas), and sea cows, as they are here (Fig. 3) as well.

Whales have been traditionally associated with
artiodactyls, as they are here (Fig. 2) as well. The hippopotamus is considered their closest living relative based on DNA data. The present data appears to invalidate the hippo connection. We’ll see what happens when the hippo is added to the large reptile tree, but it does not look promising. Not sure if tenrecs were included in the whale DNA analysis study. If not, that was an oversight.

Figure 2. The short-tailed tenrec, Hemicentetes. Other than size and tail length, this taxon shares a long list of traits with the basal whale, Maiacetus in figure 1.

Figure 2. The short-tailed tenrec, Hemicentetes. Other than size and tail length, this taxon shares a long list of traits with the basal whale, Maiacetus in figure 1. This has not been recognized previously. Skeleton image used with permission from Digimorph.org.

The tenrec Hemicentetes
(Fig. 2) shares more traits with Maiacetus than any other taxon listed. And vice versa, of course. They nest as sisters.

Another very rare tenrec,
Limnogale (29-35cm) has a long thick tail, webbed feet and a semiaquatic lifetyle. That probably seals the deal. Limnogale is nocturnal, so it is using senses underwater we can only surmise from the whale relationship. This needs more study, but Limnogale is hard to catch! And it is very rare. Click here for an image and data on Limnogale. I want more data on that tenrec, but it has not been well studied or sent to digimorph.org yet.

Figure 3. The mammals updated with the addition of a basal whale, Maiacetus, and an aardvark Orycteropus.

Figure 3. The mammals updated with the addition of a basal whale, Maiacetus, and an aardvark Orycteropus.

While Limnogale has the 
wet look and aquatic niche we are looking for in a whale ancestor. another Madagascar tenrec, Hemicentetes has skeletal data (Fig. 2) that enables comparison, but has a spiny coat (Fig. 4) like a hedgehog. Sometimes in evolution, you have to play the cards (data) you are dealt,

About tenrecs
Not typical of placental mammals, a cloaca remains present, rather than a separate anus and urogenital opening and tenrecs lack a scrotum. That shows how primitive they are. Living whales also lack a scrotum, but have separate anal and genital openings, perhaps by convergence with most other mammals. Tenrecs are omnivorous. Most tenrecs are nocturnal and have poor eyesight, but their whiskers are sensitive. Distinct from whales, tenrecs tend to have 20-32 young. Some species are social.

Figure 4. The spiny tenrec Hemicentetes with a Digimorph skull overprinted. Until skeletal data on Limnogale comes in, this short tail tenrec will have to do.

Figure 4. The spiny tenrec Hemicentetes with a Digimorph skull overprinted. Until skeletal data on Limnogale comes in, this short tail tenrec will have to do. That foramen below the orbit is retained in some basal land whales.

That little foramen
below the orbit of Hemicentetes (Fig. 4) is also found in basal whales like Dorudon (Fig. 5). Not sure what it is or was used for. That’s another paper to be written by some future grad student.

Figure 5. Dorudon skull featuring the foramina below the orbit, similar to the one in the tenrec, Hemicentetes in figure 4.

Figure 5. Dorudon skull featuring the foramen below the orbit, similar to the one in the tenrec, Hemicentetes in figure 4.

For whale ancestors 
you might like tenrecs (Fig. 6) more than hippos. The snout is long and narrow. The teeth are similar to those of whales both in pattern and size. With that long otter-like tail on Limnogale, and flexible spine on Hemicentetes, at this point we can only imagine that swimming tenrecs swim in a fashion more similar to whales than any sort of hippo could ever manage. The chest cavity is large. The feet are flat and have not developed hooves or lost digits. The tenrec/whale case may be one more instance where DNA has let us down.

Figure 6. Tenrecs now nest as sisters to whales in the large reptile tree. Here are a few other extinct land whales to scale.

Figure 6. Tenrecs now nest as sisters to whales in the large reptile tree. Here are a few other extinct land whales to scale. They are all giant aquatic tenrecs. 

This discovery made my day.
Giant aquatic tenrecs add support to this continuing study and the validity of the large reptile tree at www.ReptileEvolution.com.

This is further evidence
that you don’t have to have the fossil in front of you to add to the present body of knowledge in evolution and paleontology, despite the vocal majority that says otherwise. That restrictive paradigm has to change.

References
Gingerich PD, Ul-Haq M, von Koenigswald W, Sanders WJ, Smith BH, Zalmout IS 2009. New protocetid whale from the middle eocene of pakistan: birth on land, precocial development, and sexual dimorphism. PLoS ONE 4 (2): e4366. doi:10.1371/journal.pone.0004366