Vintana and the vain search for the clades Allotheria and Gondwanatheria

Figure 1. Vintana as originally illustrated. I added colors to certain bones. Note the high angle of the ventral maxilla and the deep premaxilla. Lateral view reduced to scale with other views.

Figure 1. Vintana as originally illustrated. I added colors to certain bones. Note the high angle of the ventral maxilla and the deep premaxilla. Lateral view reduced to scale with other views.

Earlier we looked at Vintana (Fig. 1, Krause et al. 2014a, b). To Krause et al. Vintana represented the first specimen in the clades Allotheria and Gondwanatheria to be known from more than teeth and minimal skull material.

To Krause et al. 
Allotheria included Multituberculata and nested between the clade Eutriconodonta (including Repenomamus and Jeholodens) and the clade Trechnotheria (including the spalacotheres Maotherium and Akidolestes) and Cronopio, Henkelotherium, Juramaia, Eomaia, Eutheria and Metatheria.

Taxon exclusion issues
The large reptile tree (LRT, 1005 taxa) did not recover the above clades or relationships. Alotheria does not appear in the LRT.

  1. Multituberculata, Henkelotherium and Maotherium nest within Glires (rats and rabbits and kin) in the LRT.
  2. Repenomamus and Jeholodens nest within the pre-mammalian trityllodontid cynodonts in the LRT.
  3. Akidolestes nests within basal Mammalia, close to Ornithorhynchus in the LRT.
  4. Cronopio and Juramaia nest within basal Mammalia between Megazostrodon and Didelphis in the LRT.
  5. Eomaia nests at the base of the Metatheria in the LRT.
  6. Vintana nests with Interatherium among the derived Metatheria (marsupials), with wombats, like Vombatus and Toxodon in the LRT.

Despite a paper in Nature
and a memoir of 222 pages in the Journal of Vertebrate Paleontology; despite CT scans and firsthand examination with electron microscopes; despite being examined and described by many of the biggest name and heavy hitters in paleontology… Krause et al. never understood that Vintana was just a derived wombat, evidently due to taxon exclusion problems.

Figure 3. Interatherium does not nest with notoungulates or other purported interotheres. Rather cat-sized Interatherium nests with wombats, between Vombatus and the giant Toxodon.

Figure 2. Interatherium does not nest with notoungulates or other purported interotheres. Rather cat-sized Interatherium nests with wombats,with Vintana,  between Vombatus and the giant Toxodon

The large reptile tree now includes
1005 taxa, all candidates for sisterhood with every added taxon. Despite the large gamut of 74 taxa employed by Krause et al. they did not include the best candidates for Vintana sisterhood. Perhaps the fault lies in the reliance of prior studies and paradigms. Perhaps the fault lies in the over reliance by Krause et al. and other mammal workers, on dental traits. Perhaps the fault lies in the absence of pertinent sisters to the above-named taxa, including Interatheriium for Vintana.

In any case
Vintana does not stand alone as the only taxon in its clade represented by skull material. Based on its sisterhood with Interatherium, we have  pretty good idea what its mandibles and post-crania looked like. Yes, Vintana is weird. But Interatherium is also weird in the same way, just not as weird.

The LRT has dismantled and invalidated
several other clades, too, Ornithodira and Parareptilia among them.

References
Krause DW, Hoffmann S, Wible JR, Kirk EC, and several other authors 2014a. First cranial remains of a gondwanatherian mammal reveal remarkable mosaicism. Nature. online. doi:10.1038/nature13922. ISSN 1476-4687.
Krause DW et al. 2014b. Vintana sertichi (Mammalia, Gondwanatheria) from the Late Cretaceous of Madagascar. Journal of Vertebrate Paleontology Memoir 14. 222pp.

wiki/Vintana
pterosaur heresies – Vintana

What is Darwinius?

Franzen et al. 2009
reported on a well-preserved small primate from 50mya named Darwinius.

From the Franzen et al. 2009 conclusion:
“Darwinius masillae represents the most complete fossil primate ever found, including both skeleton, soft body outline and contents of the digestive tract. Study of all these features allows a fairly complete reconstruction of life history, locomotion, and diet. Any future study of Eocene-Oligocene primates should benefit from information preserved in the Darwinius holotype. Of particular importance to phylogenetic studies, the absence of a toilet claw and a toothcomb demonstrates that Darwinius masillae is not simply a fossil lemur, but part of a larger group of primates, Adapoidea, representative of the early haplorhine diversification.”

In a published comment Beard 2009 wrote:
“Unbridled hoopla attended the unveiling of a 47-million-year-old fossil primate skeleton at the American Museum of Natural History in New York on 19 May. Found by private collectors in 1983 in Messel, Germany, the press immediately hailed the specimen as a “missing link” and even the “eighth wonder of the world.”

“Overall proportions and anatomy resemble that of a lemur, and the same is true for other adapiform primates. A new genus and species of adapiform primate, Darwinius masillae (Franzen et al., 2009; Eocene, 50 mya ). The adapids are a branch of the primate tree that leads to modern lemurs. Ida would have to have anthropoid-like features that evolved after anthropoids split away from lemurs and other early primates. Here, alas, Ida fails miserably.” The reasons for that “fail” were not listed in the Beard note.

Taxon exclusion?
The large reptile tree, (LRT, 896 taxa), currently tests only a few primates. At this stage, Darwinius does indeed nest at the base of higher primates (simians), alongside Tarsius, the extant tarsier, but there are many dozen primate taxa that have not been included in the LRT.

Figure 1. Darwinius overall plus an X-ray showing the transition from milk teeth to adult teeth in this juvenile specimen.

Figure 1. Darwinius overall plus an X-ray showing the transition from milk teeth to adult teeth in this juvenile specimen.

In the LRT,
nesting only a few primates at present, the adapid prosimian, Notharctus, is basal to higher primates including humans (genus Homo). Tarsius, the tarsier, nests between Notharctus and Proconsul, a basal anthropoid (ape). Darwinius nests with Tarsius, but lacks the many specialized autapomorphies that characterize extant tarsiers like:

  1. oversized eyes
  2. distally fused tibiafibula
  3. elongated pedal digits 4 and 5.
  4. hyperelongated astragalus and calcaneum
  5. cervicals insert further beneath the skull
Figure 2. Tarsius, the extant tarsier. Note the several autapomorphies displayed here vs. the many plesiamorphies in Darwinius.

Figure 2. Tarsius, the extant tarsier. Note the several autapomorphies displayed here vs. the many plesiamorphies in Darwinius.

Wikipedia reports
“Most experts hold that the higher primates (simians) evolved from Tarsiidae, branching off the Strepsirrhini before the appearance of the Adapiformes.” If true, Darwinius is close to the lineage of humans. “A smaller group agrees with Franzen et al. that the higher primates descend from Adapiformes (Adapoidea). The view of paleontologist Tim White is that Darwinius is unlikely to end the argument.” 

NBC news reports,
here that “Ida is as far removed from the monkey-ape-human ancestry as a primate could be, says Erik Seiffert of Stony Brook University in New York. The new analysis says Darwinius does not belong in the same primate category as monkeys, apes and humans. Instead, the analysis concluded, it falls into the other major grouping, which includes lemurs.”

Nature reports on the “media frenzy”
here in a paper entitled: A hyped-up fossil find highlights the potential dangers of publicity machines.  To be fair, the authors’ claims at the press conference were appropriately measured. Nonetheless, the researchers were fully involved in the documentaries and the media campaign, which associate them with a drastic misrepresentation of their research.”

“Another damaging aspect of the events was the unavailability of the paper ahead of the press conference and initial media coverage. This prevented scientists other than those in the team from assessing the work and thereby ensuring that journalists could give a balanced account of the research.

“There is no reason to think that PLoS ONE’s editors and reviewers did less than their duty to the paper. Nonetheless, the clock was ticking at the time of submission.”

“In principle, there is no reason why science should not be accompanied by highly proactive publicity machines. But in practice, such arrangements introduce conflicting incentives that can all too easily undermine the process of the assessment and communication of science.”

The primate experts can hash this out.
At present, with so few primates tested, Darwinius is still a candidate to be at the transition from prosimian to simian in the LRT, as it presently nests… until additional taxa knock it out.

Added within minutes of posting
I ran across this reference:
Gingerich PD et al. 2010. Darwinius masillae is a Haplorhine — Reply to  Williams et al. (2010). Journal of Human Evolution. 59(5)574-576 where they report, “Williams et al. (2010) imply that ‘total evidence’ means study of hundreds of characters in a great many taxa. However, total evidence is about combining data before analysis and not about the size of the resulting matrix. “We agree with Seiffert et al., 2009 and Williams et al., 2010, and others that there is a strepsirrhine–haplorhine dichotomy in primate evolution. We employ the same cladistic methods. We accept that total evidence drawn from many sources is advantageous. Why then do we reach such a different conclusion about the systematic position of Darwinius? Given that our methods are the same, then our contrasting results can only be explained by differences in the number and balance of taxa chosen for study, the character matrix used to analyze higher-level primate phylogeny, the outgroup chosen to root a phylogenetic network, or some combination of these.”
More details on their arguments are found here.

References
Beard C 2009. Why Ida is fossil is not the missing link. Comment, NewScientist.
Online here.
Franzen JL, Gingerich PD, Habersetzer J, Hurum JH, Von Koenigswald W and Smith BH 2009. Complete primate skeleton from the Middle Eocene of Messel in Germany: morphology and paleobiology PLoS ONE. 4 (5): e5723.

wiki/Darwinius

nature.com article that touches on Darwinius