Dublin Pterodactylus cast needs identification

This post includes updates
On Pterosaur-net.blogspot.com Dr. David Hone invited readers to identify the original specimen number to a plaster cast of a disarticulated Solnhofen long-necked pterosaur labeled Pterodactylus longicollum (Fig. 1). Matthew Parkes, a curator in Dublin, asked Dr. Hone for the help on this old (pre-1891) specimen. No scale bar was provided, but a missing label (lower left) provides some clue, whether the label was 2″ or 4″ long (probably some length in-between). Dr. Hone considered it similar in size to P. logicollum. None of Dr. Hone’s three commenters were able to provide the identification, so I re-present it to you all to help out Dr. Hone in his quest.

Figure 1. Click to enlarge. Known since the 19th century, Dublin Solnhofen Pterodactylus plaster cast needs museum number identification and link to original specimen. See figure 2 for identification of certain bones.

Sure it’s a mess, but it’s still worthy. 
Dr. Hone reported, “the unusually long and tube-like cervical centra of this taxon are visible at the upper left part of this cast and the size and gross proportions are about right (even if few details are visible).”

Figure 2. Click to enlarge. Dublin Solnhofen Pterodactylus cast with certain bones colorized and outlined. The wing ungual is enlarged and inset. This tracing has not been updated. Update can be seen in a May 26, 2013 post.

Here, using DGS, some bones were identified
It appears that a complete set of cervicals are indeed present (alternating lavender/navy blue bones arcing toward the missing label), so they are not in the upper left hand corner. Those are the radius, ulna, carpals and proximal metacarpal. The two humeri are in red. The sternal complex is brown. One wing is articulated and tipped with phalanx 5 (an ungual, see inset enlarged). The skull and mandible are seen in lateral view, slightly disarticulated, but provided with a posterior spine-like soft crest (longer than in this other specimen) and perhaps more soft-tissue surrounding it. The torso includes a jumble of ribs and the pectoral girdle. A foot appears to be present over the dorsal ribs.

Figure 4. Reconstructed Dublin cast pterosaur. It nests with No. 42 and shares many traits.

As originally identified, the long metacarpus links this specimen to Pterodactylus longicollum (recently renamed Ardeadactylus). So does the shape of the sternal complex and m4.1, which is longer than mc4. Such traits are also found in the Pterodactylus-like pre-azhdarchid clade (Fig. 4, related to Dorygnathus and Huanhepterus) including n42, n44 and Sos 2428 (n57), the flightless pterosaur (Fig. 3, upper left in blue). Before I put the extra effort into creating the reconstruction and fine tuning certain tracings I reported the above traits suggested the Dublin specimen was related to Pterodactylus longicollum, as originally considered. However, after the reconstruction was made, it appears the specimen was more closely related to the Huanhepterus clade. Still no phylogenetic analysis. That will seal the deal. It is interesting how certain members of the two clades converged.

Figure 3. Click to enlarge. The Pterodactylus lineage and mislabeled specimens formerly attributed to this “wastebasket” genus.

So, if you can help Dr. Parkes and Dr. Hone identify the museum number of this Dublin specimen, please do so.

References
Wellnhofer P 1970. Die Pterodactyloidea (Pterosauria) der Oberjura-Plattenkalke Süddeutschlands. Abhandlungen der Bayerischen Akademie der Wissenschaften, N.F., Munich 141: 1-133.

More on the origin of turtles

Earlier we looked at the origin of turtles.

This blogpost has been essentially deleted after the addition of several basal taxa to the large reptile tree. Click here for updates added Feb. 2016.

References
Li C, Wu X-C, Rieppel O, Wang L-T and Zhao L-J 2008. An ancestral turtle from the Late Triassic of southwestern China. Nature 456: 497-501.
Layson TR, Bever GS, Bhullar B-AS, Joyce WG and Gauthier JA 2010. Transitional fossils and the origin of turtles. Biology Letters June 9 2010. doi: 10.1098/rsbl.2010.0371

wiki/Odontochelys

The origin of bats (morphology vs. molecules part 2)

prEarlier we looked at the origin of bats comparing DNA models to morphological models following the publication of Meredith (2011).

Gunnell and Simmons (2005) reported, “Morphological data have almost universally placed bats in the group Archonta, together with dermopterans, primates, and tree shrews (e.g., Wible and Novacek, 1988; Beard, 1993; Simmons, 1993, 1995; Szalay and Lucas, 1993; Miyamoto, 1996). Several phylogenetic studies have suggested that bats and  dermopterans are sister taxa (together forming a clade called Volitantia), an arrangement that is appealing since dermopterans are gliding mammals and many researchers believe that bats evolved from gliding ancestors (Wible and Novacek, 1988; Simmons, 1993, 1995; Szalay and Lucas, 1993, 1996). However, an archontan relationship for bats has been strongly questioned in recent molecular studies.”

“Despite seemingly strong morphological evidence, bats have not appeared as a member of either Volitantia or Archonta in any of the more than two dozen molecular studies completed since the early 1990s. Regardless of the genes sampled or the phylogenetic methods used, bats never group with primates or dermopterans;multiple analyses of nuclear and mitochondrial gene sequences have resoundingly refuted the hypothesis that bats are archontan mammals. Instead, molecular studies uniformly place bats in a Laurasiatheria clade (e.g., Miyamoto et al. , 2000; Murphy et al. , 2001; Arnason et al. , 2002; Douady et al. , 2002; Van Den Bussche et al. , 2002; Van Den Bussche and Hoofer, 2004). Within this group, bats most commonly appear as either the sister group or basal member of a cetferungulate clade (which includes pholidotans, carnivores, cetaceans, artiodactyls, and perissodactyls) or as the sister group of a eulipotyphlan clade (including shrews, moles, and possibly hedgehogs). Accordingly, no single order of mammals appears to be the sister group of bats. Instead, bats seem to be derived from primitive mammals (i.e., basal or near basal laurasiatheres) that also gave rise to several other orders.”

So, where do we stand?
With the early Paleocene placental explosion (O’Leary et al. 2013) we have no fossils that link bats with pholidotans, carnivores, cetaceans, artiodactyls, and perissodactyls. Or do we?

And for that matter…
Where do dermopterans and primates come from?

The bat tree
The bat tree, based on morphology, nests bats close to both of these large clades, deriving them from ancient carnivores and within that clade, prehistoric vivverids (basal carnivores not far from occasionally arboreal civets). Despite their placement in the order Carnivora, civets are omnivorous, or, in the case of the Palm Civets, almost entirely herbivorous. The carnassial teeth are relatively underdeveloped.

Gunnell and Simmons (2005) report, “The fact that the most primitive known fossil bats from the early Eocene already possessed most of the derived characters of extant chiropterans (including specializations for powered flight) suggests that more primitive proto-bats were present by the late Paleocene, if not earlier.”

As in birds and pterosaurs, two hypotheses on the origin of flight in bats have been proposed: the ground-up hypothesis and the trees-down hypothesis. The ground-up hypothesis (Jepsen 1970 and Pirlot 1977) posits webbed hands for capturing terrestrial insects, followed by leaping to capture flying insects.

Evidence of a gliding ancestry for bats may be found in their resemblances to dermopterans. These groups have a number of morphological features of the hand, elbow and foot that are related to gliding, flight, and under-branch hanging (Simmons, 1995; Szalay and Lucas, 1993, 1996).

Gunnell and Simmons (2005) conclude: “Proto-bats were most likely arboreal, small, insectivorous, and nocturnal. All known Eocene fossil bats are small-bodied and have dentitions indicative of an insectivorous diet, and proto-bats probably shared these characteristics (for a discussion of bat occlusal morphology see Polly et al. , 2005). Simmons and Geisler (1998) suggested that primitive fossil bats such as Icaronycteris  and Archaeonycteris  were perch-hunting insectivores that preyed on insects found on surfaces rather than capturing aerial insects on the wing. Protobats, lacking the ability for sustained flight, would most likely have had a similar diet.”

“Like dermopterans and many megachiropterans, proto-bats were probably under-branch hangers that employed both hands and feet while hanging (Simmons, 1995). This form of suspension would have allowed small proto-bats to exploit terminal branch leaves in search of insects and would have positioned them for gliding forays between tree branches or separate trees. Proto-bats may also have had some hindlimb specializations (such as some form of tendon locking mechanism; see Szalay and Lucas, 1993; Simmons and Quinn, 1994).”

The war between morphology and molecules
Occasionally morphology does not agree with molecules. And that’s a problem. Ultimately phylogeny must rule. No matter what is happening in their DNA, juveniles more or less resemble their parents. Evolution proceeds in small generational steps.

Maybe the DNA distances are not so great as we think. 
If we look at the pertinent section of the mammal family tree we find that bats are maybe not so far from either proto-primates or proto-ungulates.

Figure 1. Mammal family tree with color showing probable origin of bats, between carnivores and port-ungulates and pro to-primates.

The Early Paleocene
When so many mammals radiate so quickly without a distinct fossil record we are left with a cave that will echo back what we yell into it. Here (Fig. 1) we find carnivores and proto-ungulates not that far from tree shrews and primates (and for that matter dermoptera (unlisted). Here’s where we’ll find the origin of bats.

Getting Down to the Genus Level
We took the origin of bats back to the extant Ptilocercus, which was a basal proprimate.  The earliest known bats, Onychonycteris and Icaronycteris and the earliest known pro carnivores, like Vincelestes, and likely proprimates extend back to the Early Cretaceous.

Figure 3. Bats and their sisters according to the DNA results of Meredith et al. 2011. Note the rapid branching at the base, which also extends to the base of the primates + dermopterans. 

So, what looks like a huge DNA gap, may be a small one.
At the time that proto-primates diverged from proto-bats and other proto-placentals, there was, evidently, little morphological difference between them, having radiated so recently from a common ancestor, something like Ptilocercus. In this regard, perhaps flying lemurs and bats represent some of the most primitive members of this clade, despite their subsequent DNA departures.

Just trying to find common ground
Such a DNA vs. morphology problem rears its ugly head again in the large reptile tree and its nesting of synapsid mammals closer to diapsid crocs and birds, leaving turtles and lizards + snakes on another branch, but DNA does not bear this out. Not sure how that one will ever be resolved.

I trust DNA. I also trust phylogenetic analysis. There is so much common ground in non-problem areas, I hope to find some common ground in problem areas.

As always, I encourage readers to see specimens, make observations and come to your own conclusions. Test. Test. And test again.

Evidence and support in the form of nexus, pdf and jpeg files will be sent to all who request additional data.

References
Arnason U, Adegoke JA, Bodin K, Born EW, Esa YB, Gullberg A, Nilsson, M, Short RV, Xu X, and Janke A 2002. Mammalian mitogenomic relationships and the root of the eutherian tree. Proc. Natl. Acad. Sci. U.S.A 99: 8151.
Beard KC 1993. Origin and evolution of gliding in early Cenozoic Dermoptera (Mammalia, Primatomorpha). In: Primates and Their Relatives in Phylogenetic Perspective, R. D. E. MacPhee, ed., pp. 63–90, Plenum, New York.
Gunnell, GF and Simmons NB 2005. Fossil evidence and the origin of bats. Journal of Mammalian Evolution 12: 209-246 (2005).
Jepsen GL1970. Bat origins and evolution. In: Biology of Bats 1, W. A. Wimsatt, ed., pp. 1–64, Plenum, New York.
Meredith RW et al. 2011. Impacts of the Cretaceous Terrestrial Revolution and KPg Extinction on Mammal Diversification. Science 334:521-524.
Miyamoto MM 1996. A congruence study of molecular and morphological data for eutherian mammals. Mol.Phylogenet. Evol. 6: 373.
Miyamoto MM, Porter C and Goodman M 2000. cMyc gene sequences and the phylogeny of bats and other eutherian mammals. Syst. Biol. 49: 501.
Murphy WJ, Eizirik E, Johnson WE, Zhang YP, Ryder OA and O’Brien SJ 2001. Molecular phylogenetics and the origin of placental mammals. Nature 409: 614.
O’Leary, MA et al. 2013. The placental mammal ancestor and the post-K-Pg radiation of  placentals. Science 339:662-667. abstract
Simmons NB 1993. The importance of methods: Archontan phylogeny and cladistic analysis ofmorphological data. In: Primates and Their Relatives in Phylogenetic Perspective, R. D. E. MacPhee, ed., pp. 1–61, Plenum, New York.
Simmons NB 1995. Bat relationships and the origin of flight. In: Ecology, Evolution and Behavior of Bats, PA Racey and SM Swift, eds., Symp. Zool. Soc. Lond. 67: 27.
Szalay FS and Lucas SG 1993. Cranioskeletal morphology of archontans, and diagnoses of Chiroptera, Volitantia, and Archonta. In: Primates and Their Relatives in Phylogenetic Perspective, R. D. E. MacPhee, ed., pp. 187–226, Plenum, New York.
Wible JR and Novacek JM1988. Cranial evidence for the monophyletic origin of bats. Am. Mus. Novit.v2911: 1.
Wible JR, Rougier GW, Novacek MJ, Asher RJ 2007. Cretaceous eutherians and Laurasian origin for placental mammals near the K/T boundary Nature 447: 1003-1006

The Skull of Lotosaurus (the finback poposaurid dinosaur)

Figure 1. The skull of Lotosaurus color coded. This toothless poposaurid nests with the herbivorous Silesaurus and Pseudolagosuchus (Fig. 2), neither of which have a fin. This is a DGS tracing.

Lotosaurus is interesting and mysterious because it is so big and so derived, yet appears so early (early Middle Triassic), essentially earlier than all other known dinosaurs. If phylogeny is a guide, then dinosaurs, notably theropods, originated earlier than this. Maybe there was a dino explosion in the early Triassic matching the placental explosion in the early Paleocene. We just haven’t found evidence for it yet.

Lotosaurus really needs a fresh new paper and a complete redescription. To that point, Nesbitt (2011) reports, “A full description of Lotosaurus is currently underway.” We’ve seen recent papers on Arizonasaurus (Fig. 1, an unrelated rauisuchian) and Ctenosauriscus (Fig. 2, too soon to know what it is), but really nothing recent on Lotosaurus (Zhang 1975), which currently nests with poposaurid dinosaurs. It would be nice to know what’s real and what isn’t, how many specimens we have (Wiki says 10), and if new data changes hows it currently nests.

Earlier we looked at other finbacks and possible sister taxa. The skull of Silesaurus is a pretty close match to that of Lotosaurus, sans the teeth and adding some bulk. The rest of the changes in morphology appear to reflect the return to a quadrupedal stance along with greater bulk and loss of teeth.

Figure 3. Lotosaurus compared to sister taxa and other finback archosaurs.

Nesbitt (2003) reported on Arizonasaurus. He wrote, “Characterisitics of the skeleton of Arizonasaurus show that it belongs to a poorly known group of Middle Triassic (240–230 Myr ago) archosaurs called the ctenosauriscids, and that ctenosauriscids are or are closely related to poposaurs. Furthermore, many characteristics of Arizonasaurus provide evidence that poposaurids and ctenosauriscids are derived rauisuchians.”

Dinosaurs are also derived from basal rauisuchians, but that’s not what Nesbitt meant. Nesbitt considered Arizonasaurus a derived rauisuchian, but the large reptile tree nested it close to the basal taxon, Vjushkovia. Nesbitt’s (2003) analysis did not include Lotosaurus, but his 2011 study did, nesting it between Poposaurus and Sillosuchus, Effigia and Shuvosaurus, with rauisuchians and far from Silesaurus, which Nesbitt (2011) nested just outside the Dinosauria. We earlier discussed problems with Nesbitt (2011) and his “strange bedfellows” in a nine-part  series. It’s worthwhile to also recall that certain poposaurs developed a new calcaneal tuber, convergent with the development of a calcaneal heel in crocodylomorphs. Such a structure traditionally removes poposaurids from the Dinosauria, but phylogenetic analysis puts them back in. Lotosaurus had a very small calcaneal tuber, if any. It’s hard to see on existing data.

I’ll be out for a week on family business. See you again after the 25th.

As always, I encourage readers to see specimens, make observations and come to your own conclusions. Test. Test. And test again.

Evidence and support in the form of nexus, pdf and jpeg files will be sent to all who request additional data.

References
Butler RJ, Brusatte SL, Reich M, Nesbitt SJ, Schoch RR, et al. 2011. The Sail-Backed Reptile Ctenosauriscus from the Latest Early Triassic of Germany and the Timing and Biogeography of the Early Archosaur Radiation. PLoS ONE 6(10): e25693. doi:10.1371/journal.pone.0025693 Plos One paper
Nesbitt SJ 2003. Arizonasaurus and its implications for archosaur divergence
Sterling J. Nesbitt Proceedings of the Royal Society, London B (Suppl.) 270, S234–S237. DOI 10.1098/rsbl.2003.0066
Nesbitt SJ 2011. The early evolution of archosaurs: relationships and the origin of major clades. Bulletin of the American Museum of Natural History 352: 292 pp.
Weinbaum JC and Hungerbuhler A 2007. A Revision of Poposaurus gracilis (Archosauria: Suchia) based on two new specimens from the Late Triassic of the southwestern USA. Palaeontologische Zeitschrift 81(2):131-145.
Zhang F-K 1975. A new thecodont Lotosaurus, from Middle Triassic of Hunan. Vertebrata PalAsiatica 13:144-147.

wiki/Lotosaurus

Non-dinosaurian Dinosauromorpha (Langer et al. 2013)

Continuing to push Lagerpeton as a “dinosauromorph” (which is traditional thinking), Langer et al. (2013) continues to ignore certain basic facts starting in the feet that divide pararchosauriforms (including Lagerpeton) and euarchosauriforms (including dinosaurs) into two major clades.

Figure 1. Click to enlarge. The feet of Euarchosauriformes (above in white) and Pararchosauriformes (below in grey). No higher euarchosauriformes have a longer digit 4 than 3. Both clades share more foot traits with each other, which removes Lagerpeton from the lineage of dinosaurs in the Euarchosauriformes, and puts it in the line of descent from Diandongosuchus (with its long digit 4) and/or Proterochampsa (with its short digit 1). Also note that the ascending process of the astragalus is posterior in Lagerpeton, anterior in dinosaurs.

Euarchosauriformes
It’s unfortunate that so few euarchosauriform feet are known that include a complete digit 4, but what we do know demonstrates that digit 4 is always shorter than 3 and metatarsal 4 is always shorter than mt3.

Pararchosauriformes
In this clade pedal digit 4 can sometimes be longer than 3 and metarsal 4 is never shorter than mt3. Sometimes pedal digit 4 is reduced to a vestige, other times, even within a genus, it is not. In any case, Lagerpeton belongs in this clade, a small biped at the acme of a  large, flat-headed, quadrupedal clade. It does not belong with dinosaurs or their short pedal digit 4 kin. In Lagerpeton, the astragalus flange rises in back of the tibia, not in the front, as in dinosaurs.

The way to separate the Euarchosauriformes from the Pararchosaurifomes
is to introduce protorosaurs, Youngina, Youngoides, Choristodera, Doswellia and the traditional archosauriformes, as demonstrated by the large reptile tree.

Mistaking Early Triassic bipedal lizard tracks for dinosauromorph tracks
Earlier we discussed the mistakes of Brusatte et al. (2012) who claimed that certain ichnites related to Rotodactylus in the Early Triassic belonged to lagerpetids, when in reality they belong to cosesaurids, in the ancestry of pterosaurs.

As always, I encourage readers to see specimens, make observations and come to your own conclusions. Test. Test. And test again.

Evidence and support in the form of nexus, pdf and jpeg files will be sent to all who request additional data.

References
Langer MC, Nesbitt SJ, Bittencourt JS and Irmis RB 2013.  Non-dinosaurian Dinosauromorpha.  Geological Society, London, Special Publications v.379, first published February 13, 2013; doi 10.1144/SP379.9 From: Nesbitt SJ, Desojo JB and Irmis RB eds) Anatomy, Phylogeny and Palaeobiology of Early Archosaurs and their Kin. Geological Society, London, Special Publications, 379, http://dx.doi.org/10.1144/SP379.9 # The Geological Society of London 2013.

Normannognathus – Not a Germanodactylid. Not a Dsungaripterid.

Normannognathus wellnhoferi (Buffetaut et al. 1998, boxed lower left in Fig. 1 and at right in Fig. 2) is represented by a broad, long, toothy rostrum with a midrostral crest and a matching dentary. Most of the teeth are absent, but their root cavities remain. It has been widely and wrongly considered a dsungaripterid pterosaur from the Late Jurassic of Normandy, France.

Figure 1. Diopecephalus = P. longicollum = Ardeadactylus. Normannognathus is in the box in the lower left. Note there is no pointed snout here. The teeth continue around the front. Even the size is right compared to the more complete pterosaur skeleton with widely splayed teeth.

Dsungaripterid and germanodactylid pterosaurs are identified by their pointed, single-tooth jaw tips, and that is not the case in Normannognathus. (What were they thinking??) Rather the teeth line the entire rim of the both jaws, rather more like Pterodactylus longicollum (Fig. 1), with whom it more precisely nests. This makes Normannognathus an odd crested Pterodactylus.

Figure 12. Normannognathus compared unfavorable to Dsungaripterus. Artist unknown.

As always, I encourage readers to see specimens, make observations and come to your own conclusions. Test. Test. And test again.

Evidence and support in the form of nexus, pdf and jpeg files will be sent to all who request additional data.

References
Buffetaut  E, Lepage J-J and Lepage G 1998. A new pterodactyloid pterosaur from the Kimmeridgian of the Cap de la Hève (Normandy, France). Geological Magazine 135:719-722

Giant Pterodactylus in the Cretaceous

All we have
are a pair of cervical vertebrae from the paratype (de Buisonjé 1980) named Santandactylus brasiliensis (Aptian, Brazil, Fig. 1). The closest match is to Pterodactylus longicollum (Fig. 1), otherwise known as Ardeadactylus (Bennett 2013), the largest Solnhofen pterosaur in the lineage of the holotype of Pterodactylus antiquus. Santandadactylus brasiliensis was the largest known pterosaur in the Pterodactylus lineage and extends this lineage past the Late Jurassic. The Aptian is in the late Early Cretaceous.

Figure 1. Santanadactylus brasiliensis, is not an ornithocherid or tapejarid, like so many other contemporary pterosaurs. It appears closest to Pterodactylus longicollum from the Late Jurassic of the Solnhofen formation. 

Okay, so it’s not a giant pterosaur.
But Santanadactylus brasiliensis is a giant Pterodactylus If it follows in the pattern of post-Jurassic Germanodactylus, then we might expect to see some cresting here when the skull becomes known. That little crested skull in the box in the lower left had corner is Normannognathus, which we’ll look at next.

Rumor
We’ll discuss the really giant Pterodactylus (much taller than a human) when the paper gets published.

As always, I encourage readers to see specimens, make observations and come to your own conclusions. Test. Test. And test again.

Evidence and support in the form of nexus, pdf and jpeg files will be sent to all who request additional data.

References
de Buisonjé, PH1980. Santanadactylus brasiliensis nov.gen. nov.sp. a longnecked, large pterosaur from the Aptian of Brazil. Proceedings of the Koninklijke Nederlandse Akademie van Wetenschappen B 83(2):145-172.

Post K-T Explosion of Placentals – O’Leary et al. 2013

Updated Set 30, 2016 with new data on bat ancestors and additional taxa.

A new paper by O’Leary et al. (2013) brings new insight into the earliest radiation of placental mammals. This happened in a great radiation of clades right after the K-T extinction event, according to their results. This counters claims that placentals may have been present during the Cretaceous, but their fossils have not been found yet. Monotremes and metatherians, the ancestors of today’s egg-laying and marsupial mammals, were present during the Cretaceous. Other lineages of mammals, like Morganucodon, were present as far back as the Triassic. So that means relative stasis throughout much of the Mesozoic for mammals, followed by explosive radiation in the first third of the Paleocene.

Figure 1. Left: A hypothetical placental ancestor enjoying the insects of the Palaeocene. Right: Ukhaatherium, Late Cretaceous Mongolian mammal.

The O’Leary et al. abstract: To discover interordinal relationships of living and fossil placental mammals and the time of origin of placentals relative to the Cretaceous-Paleogene (K-Pg) boundary, we scored 4541 phenomic characters de novo for 86 fossil and living species. Combining these data with molecular sequences, we obtained a phylogenetic tree that, when calibrated with fossils, shows that crown clade Placentalia and placental orders originated after the K-Pg boundary. Many nodes discovered using molecular data are upheld, but phenomic signals overturn molecular signals to show Sundatheria (Dermoptera + Scandentia) as the sister taxon of Primates, a close link between Proboscidea (elephants) and Sirenia (sea cows), and the monophyly of echolocating Chiroptera (bats). Our tree suggests that Placentalia first split into Xenarthra and Epitheria; extinct New World species are the oldest members of Afrotheria.

O’Leary et al. (2013) nested the tree shrews, Ptilocercus and Tupaia together.
And by gum, they do look alike (Fig. 3). And I suppose their DNA looks alike. My own, more focused studies (Fig. 2), using these extant and fossil taxa, separated these two. (Granted this set excludes several mammal clades, and that may be a problem).  Ptilocercus nested between carnivorans and bats + flying lemurs, while Tupaia nested at the base of rabbits, not far from Plesiadapis and Notharctus. Several traits support these nestings and the two tree shrews are distinct in several regards (Fig.3), not least of all, their teeth. In any case these two “living fossils,” virtually unchanged for 60 million years, give some of the clearest pictures on what basal mammals looked like and what they were doing.

Figure 2. Bat origins cladogram. Here Onychonycteris and Pteropus represent bats.

In the bat study (Fig 2) only one tree shrew, Ptilocercus, nests with Cynocephalus, the “flying lemur.” In the O’Leary et al. study, both tree shrews nest with Cynocephalus.

In the bat study, (Fig. 2) bats nested close to “flying lemurs” arising out of civet-like carnivores. In the O’Leary et al. study bats nested between carnivores and proto-ungulates.

In both the bat study and the O’Leary et al. study rabbits nest with primates and this clade is kin to insectivores and carnivores in that order.

So there is some agreement here.
The big problem is keeping dermopterans (“flying lemurs”) and bats together vs. separating them. This is a bigger problem when you realize that embryo bats and dermopterans both have long webbed fingers and share many other traits. But dermopterans are plant-eaters from a long way back and that may undermine what traits are now shared with insectivorous bats. Sure, megabats are fruit-eaters, but that appears to be a more recent acquisition. They still have, what appears to be, a less-derived carnivore-looking dentition, but softened and rounded in more recent times.

Figure 3. Ptilocercus and Tupaia, two living tree shrews, “living fossils” largely formed during the Paleocene. The double-rooted or fused incisors of Ptilocercus ally it with flying lemurs. It also retains a more carnivore-like dentition and a larger cranium. According to the tree in figure 2, Ptilocercus evolved from larger carnivore ancestors. Tupaia does not appear to have a larger-size ancestry.

I wonder if tree shrews nest together because they are both living fossils? The both appear to represent very primitive (Paleocene) members of the Mammalia, from a time when there were fewer and far less diverse fauna out there. Perhaps their similar DNA reflects this.

It’s a puzzlement. 
I wish I knew more about DNA in tree shrews, bats and dermopterans. If someone wants to clue me in, that would be great.

References
Wible JR, Rougier GW, Novacek MJ, Asher RJ 2007. Cretaceous eutherians and Laurasian origin for placental mammals near the K/T boundary Nature 447: 1003-1006
O’Leary, MA et al. 2013. The placental mammal ancestor and the post-K-Pg radiation of  placentals. Science 339:662-667. abstract

ArchibaldEtAl.pdf

protungulatum-donnae website

An Assault on the Large Reptile Tree (dino section)!

Note added after publication: For those interested the comments section sheds new light. 

Mickey Mortimer, blogger of the Theropod database, put a lot of work into rescoring the dinosaur portion of the large reptile tree. With those changes, here is the recovered tree (taxa abbreviated but those in the know will know).

|–Turfano
`–+–Gracili
`–+–Arizona
`–+–+–Loto
|  `–+–Popo
|     `–+–Effi
|        `–Shuvo
`–+–+–Pseudolago
|  `–Sile
`–+–Mara
`–+–Pisano
`–+–+–Scelido
|  `–+–Heterodonto
|     |–Hexinlu
|     `–+–Agili
|        `–+–Lesotho
|           `–Scutello
`–+–+–Masso
|  `–+–Theco
|     `–Saturn
`–+–Daemono
`–+–+–Panphag
|  `–Pampa
`–+–Herrera
`–+–Trial
|–SMNS
|–Tawa
`–Coelo

You’ll note that Saurischia is recovered with [Sauropodomorpha + Theropoda]. Panphagia + Pampadromaeus nest basal to Theropoda, and the [poposaurids + Arizonasaurus] nest close to the basal archosaur/crocodylomorph, Gracilisuchus. Ornithischians are in the middle.

Figure 1. A segment of the large reptile tree, focused on the Dinosauria.

These are different nestings from the large reptile tree (Fig. 1). Basically the Dinosauria has been flipped top to bottom.

Well, then, let’s test the Mortimer tree
You’ll recall when I removed taxa, clades, or large numbers of clades from the large reptile tree, the rest of the topology did not change. When I tested only skulls or only post-crania, the tree did not change. These are signs of stability and strength.

However,
when I removed the [poposaurs + Arizonasaurus] from the Mortimer tree, the topology reverted to that of the large reptile tree. That’s a big change. And there’s more:

Note
In the Mortimer tree theropods nest as the most derived clade of dinos, preceded by several clades of herbivores in this pattern:

Quoting from my reply to MM: “Turfanosuchus and Gracilisuchus (carnivores) at the base giving rise to Poposaurids (herbivores), then Silesaurids (herbivores), then Marasuchus (carnivore), then Pisanosaurus (herbivore), then a split between Ornithischians (herbivores) and Saurischians led by Sauropodomorphs on one branch (herbivores) and Daemonosaurus (?-vore) at the base of Panphagia + Pampadromaeus (herbivores) and theropods (carnivores). As you can see this is a varied mix of herbies and carnies, which is not the case in the Large Reptile Tree”

In the LRT the theropods nested as basal dinos, giving rise via Panphagia, Pampadromaeus and Daemonosaurus to herbivorous sauropodomorphs, poposaurids and ornithischia. Basically the same tree, just flipped top to bottom.

Not sure yet what ordering, scoring, what-have-you turned the Mortimer tree upside-down, but having theropods as derived and widely separating Gracilisuchus from Herrerasaurus raises red flags. It just ain’t right. Isn’t it more tenable that certain theropods gave rise to herbivores, first with saurischian pelves and later with ornithischian pelves?

The unstable topology is also bothersome. Removing taxa should not upset the topology. Hopefully we’ll come to a resolution on this. The devil is probably in the details many or all of which can be seen here at M. Mortimer’s blog post.

Arizonasaurus does not belong here. It nests with rauisuchians and shares few to  no synapomorphic traits with Gracilisuchus, a basal crocodylomorph.

I appreciate the work by MM and, perhaps, some of the rescoring is justified. I don’t know. In any case, the results do not appear to be tenable.

As always, I encourage readers to see specimens, make observations and come to your own conclusions. Test. Test. And test again.

Evidence and support in the form of nexus, pdf and jpeg files will be sent to all who request additional data.

Why an Increased Brain Capacity in Cosesaurus?

Derived from the basal lizard, Huehuecuetzpalli (Fig. 1), tritosaurs branched off in four distinct directions.

Figure 1. The mother of all pterosaurs, tanystropheids and drepanosaurs, Huehuecuetzpalli

Macrocnemus (Figs. 2-3) represents a long-necked terrestrial/marine clade culminating in Dinocephalosaurus and three other directions.

Jesairosaurus represents a long-necked, slow-moving arboreal clade culminating in the hook-tailed Megalancosaurus and Drepanosaurus.

Figure 2. Tanystropheus and kin going back to Huehuecuetzpalli.

Amotosaurus represents a long-necked terrestrial clade culminating in Langobardisaurus and Tanystropheus, some of which ventured into marine environs.

Cosesaurus (Fig. 3) represents a short-necked terrestrial clade culminating in Sharovipteryx, Longisquama and pterosaurs, which ventured into arboreal and aerial environs.

Among these four clades, Cosesaurus and kin appear to have had the larger cranium (red line in Fig. 1), both in length and depth. Why?

The answer is not neotony.
As demonstrated by Huehuecuetzpalli (Fig. 1) and pterosaurs, these taxa grew isometrically. Hatchlings and juveniles did not have larger eyes and a shorter rostrum. Now, with that said, what happened early on inside the egg, likely carried nearly to full term by the mother, is probably a different matter.

Clues to the answer for the bigger cranium and brain
may lie in the coracoids and pelvis of Cosesaurus.

Figure 3. Various tritosaur lizards shown to scale and their skulls portrayed to the same snout-occiput length. Red line represents the estimated cranial length. Note that in Cosesaurus, not only is the length longer, but the dorsal bulge is greater.

Each of these taxa (Fig. 3) were quadrupeds, but Langobardisaurus and Cosesaurus were facultative bipeds in the manner of living lizards capable of bipedal locomotion. Narrow gauge, digitigrade and occasionally bipedal tracks with pedal digit 5 far behind the others are identified as Rotodactylus (Peabody 1948) tracks and they match the pedes of these two taxa (Peters 2000, Reneto et al. 2002).

The ilium in all four taxa (Fig. 1) are anteroposteriorly long, but more so in Cosesaurus. Such a morphology is associated with bipedal locomotion in various reptiles, like theropod dinosaurs. Bipedal capabilities free the forelimbs to do something other than support the body on the substrate.

In Langobardisaurus the manus remains small without much change from Macrocnemus.

However in Cosesaurus and Jesairosaurus the hand is relatively larger with longer medial metacarpals and longer medial digits. In Cosesaurus the anterior coracoid is eroded away by enlargement of the fenestrations until just the immobile quadrant-shaped posterior rim remains. This is an indicator of flapping, as we discussed earlier. In Cosesaurus the ulna is trailed by filaments (Ellenberger 1993, Peters 2009), the precursors of aktinofibrils in pterosaur wings. In Cosesaurus, such filaments would have only added to its retinue of extradermal decorations, but these could be animated by virtue of flapping. There was also a pteroid on Cosesaurus (Peters 2009, a former centralia, now migrated to the pre-axis of the radius), which in pterosaurs anchors and partially frames a propatagium, which is a flight membrane that also keeps the elbow from overextending.

Flapping, it would appear, was a social, territorial and secondary sexual trait and if so, Cosesaurus likely competed with other cosesaurs. The need for added coordination while a biped, while flapping excitedly to woo a mate, while watching out for competitors, while shrinking in overall size all may have served to increase the relative size of the cranium in Cosesaurus. The higher needs for coordination and social display seem to have supported the enlargement of the brain. At least that’s how it appears from here.

The relatively large size of the cranium is not continued in pterosaurs, which often, but not always (think: anurognathids) have an elongated rostrum to hyper-elongated rostrum (think ctenochasmatids, ornithocheirids and pteranodontids).

And birds?
In Archaeopteryx and its closest kin there is a similar and convergent expansion of the cranium that is otherwise not expressed in other nonvolant Meszoic bird-like taxa, like oviraptorids and veloceraptorids, but is present in Ichthyornis and living birds.

So, even in this regard, Cosesaurus can be considered “the Archaeopteryx of pterosaurs,” no matter the persistent rumors that such a creature remains unknown to science.

As always, I encourage readers to see specimens, make observations and come to your own conclusions. Test. Test. And test again.

Evidence and support in the form of nexus, pdf and jpeg files will be sent to all who request additional data.

References
Ellenberger P and de Villalta JF 1974. Sur la presence d’un ancêtre probable des oiseaux dans le Muschelkalk supérieure de Catalogne (Espagne). Note preliminaire. Acta Geologica Hispanica 9, 162-168.
Ellenberger P 1978. L’Origine des Oiseaux. Historique et méthodes nouvelles. Les problémes des Archaeornithes. La venue au jour de Cosesaurus aviceps (Muschelkalk supérieur) in Aspects Modernes des Recherches sur l’Evolution. In Bons, J. (ed.) Compt Ren. Coll. Montpellier12-16 Sept. 1977. Vol. 1. Montpellier, Mém. Trav. Ecole Prat. Hautes Etudes, De l’Institut de Montpellier 4: 89-117.
Ellenberger P 1993. Cosesaurus aviceps . Vertébré aviforme du Trias Moyen de Catalogne. Étude descriptive et comparative. Mémoire Avec le concours de l’École Pratique des Hautes Etudes. Laboratorie de Paléontologie des Vertébrés. Univ. Sci. Tech. Languedoc, Montpellier (France). Pp. 1-664.
Peabody FE 1948.  Reptile and amphibian trackways from the Lower Triassic Moenkopi formation of Arizona and Utah.  University of California Publications, Bulletin of the  Department of Geological Sciences 27: 295-468.
Peters D 2000a. Description and Interpretation of Interphalangeal Lines in Tetrapods.  Ichnos 7:11-41.
Peters D 2000b. A Redescription of Four Prolacertiform Genera and Implications for Pterosaur Phylogenesis. Rivista Italiana di Paleontologia e Stratigrafia 106 (3): 293–336.
Peters D 2009. A reinterpretation of pteroid articulation in pterosaurs. Journal of Vertebrate Paleontology 29: 1327-1330.
Renesto S, Dalla Vecchia FM and Peters D 2002. Morphological evidence for bipedalism in the Late Triassic Prolacertiform reptile Langobardisaurus. Senckembergiana Lethaea 82(1): 95-106.

wiki/Cosesaurus