Pteranodon – Chimaeras and Fakes – part 2

Go to the KU natural history museum at the University of Kansas at Lawrence and downstairs you fill find a spectacular mounted Pteranodon (KU VP 2212)  in all of its glory. You might be disappointed only by the lack of a traditional long or tall crest on the cranium.

Figure 1. A Pteranodon chimaera created from the bones of several species. KU VP 2212.

Figure 1. A Pteranodon chimaera created from the bones of several species. KU VP 2212.

Upon closer inspection — It’s not just one specimen, but many
Created, like a Frankenstein monster from the dead bodies of several individuals and probably different species, the KUVP 2212 mounted specimen (Fig. 1) is nevertheless spectacular to behold. Be wary though of using all of its bits and pieces in phylogenetic analysis for therein lies madness. They say this specimen is a composite, or chimaera, of twenty specimens. Even the two feet came from different individuals (Fig. 2), at least one of which was flat-footed, distinct from other Pteranodon pedes.

Figure 2. A reconstruction of the chimaera that is KU VP 2212. Created from several individuals and several species, this mounted specimen cannot be used in toto in phylogenetic analysis.

Figure 2. A reconstruction of the chimaera that is KU VP 2212. Created from several individuals and several species, this mounted specimen cannot be used in toto in phylogenetic analysis.

The skull
belongs to a mid-sized species near the node at which the tall-crested P. sternbergia clade split from the long-crested P. ingens clade. Compared to other more complete specimens, like the Triebold specimen (Fig. 3), the skull of the KU specimen is inappropriately small. Earlier we looked at an artist who reconstructed his Pteranodon with a too small skull. Wonder if this was the inspiration?

The Triebold Pteranodon, one of the most complete ever found. The metacarpals are quite a bit longer here. So is the beak.

Figure 2. The Triebold Pteranodon, one of the most complete ever found. Compare the proportions with KU VP 2212, which is a next of kin phylogenetically (at least with regards to the skull.) This specimen is basal to the P. sternbergia clade of tall crested Pteranodon.

The flat foot of the KU specimen
belongs to a member of the P. sternbergia clade because another member, the Alberta Pteranodon, has similar proportions.

My what big arms you have!
The monster antebrachiumu of the KU specimen belong to the P. ingens clade, which also have digitgrade pedes.

The very short femur
means it probably belonged to a smaller, generally more primitive species of Pteranodon, like P. occidentals. The lack of more than a few reasonably complete Pteranodon specimens hinders more precise identification. Not sure yet about the field notes for the KU specimen. There is no paper focused on just it.

Complete specimens are hard to come by.
Museums needed large spectacular mounts to drive in their audience. The old way of thinking was: “Why not create a chimaera? After all, who’s going to know?”

It’s not exactly deception,
but creating a chimaera display mount is a practice from the past that hopefully will no longer be considered viable as interest in these fossils and their phylogeny becomes more serious.

I’ll tackle another Pteranodon chimaera as #7 in this series.

A paper written on fossil fakes is online here.

Baby Dimetrodon – Chimaeras and Fakes – Part 1

Many have seen this cast (fig. 1) entitled, “Baby (or Juvenile) Dimetrodon.” It’s a common piece of plaster merchandise sold at fossil fairs, etc.

Is it a complete fake?
The specimen has not been illustrated in the literature (that I know of), but it has been described (Sternberg 1942) and the description is a perfect match. Parts (Fig. 1 in gray) have been added to the cast to make it more interesting and complete. Sternberg (1942) reported the specimen was originally at the Walker Museum in Chicago, but in 1953 most Walker paleo exhibits, perhaps including this one, were moved to the Field Museum.

Figure 1.  Sternberg 1942 described this specimen he attributed to a baby or juvenile Dimetrodon. Parts added by artisans are in gray.

Figure 1. Sternberg 1942 described this specimen he attributed to a baby or juvenile Dimetrodon. Parts added by artisans are in gray.

On the plus side
One of the more complete Permian fossils is this baby/juvenile Dimetrodon (Sternberg 1942, Figs. 1, 2), less than a quarter the size of an adult with a much shorter sail and much longer legs. If this is a juvenile Dimetrodon, these proportions change allometrically during growth. The mandible was slightly shorter, compared to the adult, indicating the skull was likewise not larger relative to the body.

Click to enlarge. Figure 1. Baby Dimetrodon (above) compared to adult (below) to the same scale and to different scales. Note the smaller sail and longer legs and tail. Regressing the baby to egg size suggests the sail developed after hatching.

Figure 2. Click to enlarge. Figure 1. Baby Dimetrodon (above) compared to adult (below) to the same scale and to different scales. This is the first reconstruction of this specimen that I am aware of. Restored parts in light red. Note the smaller sail and longer legs and tail in the juvenile.  Regressing the baby to egg size suggests the sail developed after hatching. I’m curious about the rib length from front to back on the juvenile, different from the adult.

So, longer legs on a juvenile synapsid?
That’s not the pattern we see in mammals or Heleosaurus, a varanopid(?) protodiapsid in which adults have the longer legs. In Dimetrodon the juveniles didn’t have marginally longer legs. Juveniles had legs relatively twice as long as those on adults. Generally longer legs provide more speed to attack prey or avoid predators.

Is this really a baby Dimetrodon?
Or is it a different smaller species? Bakker(1982) suggested different habitats for Permian juveniles would help them avoid adult predation. Brinkman (1988)  cast doubt on Bakker’s idea by showing that the specimens found in floodplain and swamp sediments represented two different species, not adult and juvenile populations of the same species.

Do we need more tiny specimens and a few teenage specimens to help determine what the situation is here? Both sides make sense.

Sternberg (1942) wrote,
“The preservation of the bone is poor: It is probable that the bony elements were never well ossified.” He also wrote that three or four partial skeletons of Dimetrodon grandis were found in the same pocket, which lies in the breaks of Coffee Creek in Baylor County, Texas. If we assume those were adults, there goes Bakker’s and Brinkman’s hypotheses. Brinkman did not reference the Sternberg paper, but noted that poor ossification attended smaller Dimetrodon specimens.

Only parts are fake
Just because parts of this specimen have been added with restoration, doesn’t mean the rest of the skeleton is useless or should be labeled “a fake.” In this case, we should use what is real and avoid what is fake. The size and proportion relationships are still good data that make a good story.

References
Bakker RT 1982. Juvenile-Adult Habitat Shift in Permian Fossil Reptiles and Amphibians. Science 217 (4554): 53–55. doi:10.1126/science.217.4554.53.PMID 17739981.
Brinkman D 1988. Size-independent criteria for estimating relative age in Ophiacodon and Dimetrodon (Reptilia, Pelycosauria) from the Admiral and lower Belle Plains formations of west-central Texas. Journal of Vertebrate Paleontology 8 (2): 172–180.
Sternberg CW 1942. The skeleton of an immature pelycosaur, Dimetrodon cf. grandis, from the Permian of Texas. Journal of Paleontology 16 (4): 485–486.

A paper written on fossil fakes is online here.

Reptile Phylogram Updated

As promised, updates arrive, but not always promptly.

Here is an updated phylogram of the large reptile tree placed against a time scale. Due to the large number of taxa (340+) it is quite impossible to read this unless you download the PDF file. Then there’s no limit to its magnification.

A phylogram differs from a cladogram in showing the amount of change between taxa by the length of the horizontal bars. Longer bars indicate greater morphological change.

Figure 1. The new phlogram of the Reptilia and its outgroups. Click for pdf file. Even at this scale the diphyletic nature of the Reptilia is readily apparent, as is the great flowering of reptiles in the Permian and Triassic.

Figure 1. The new phlogram of the Reptilia and its outgroups. Click for pdf file. Even at this scale the diphyletic nature of the Reptilia is readily apparent, as is the great flowering of reptiles in the Permian and Triassic.

Some key features

1. Sometime during the Carboniferous (Mississippian + Pennsylvanian) reptiles had their origin and their original split, but not much happened or is known about them from that remote time. Reptiles remain in the minority (it was the age of Amphibians) and no great radiations occurred then.

2. The Permian was a time of great radiation for both the Archosauromorph and Lepidosauromorph lines. Among the former, synapsids paralleled proto-diapsids and early diapsids. Among the latter large diadectomorphs and pareiasaurs dominated.

3. During the PermoTriassic extinction event only a few lineages made it through.

Among the new Lepidosauromorphs the turtles (Proganochelys) and the lepidosaurs (Paliguana, Lacertulus) survived.

Among the new Archosauromorpha three main lines survived. Certain Permian synapsids evolved to become Triassic protomammals and Jurassic mammals. Dicnynodonts also made it through.

Permian enaliosaurs like Claudiosaurus and Stereosternum gave rise to a large marine radiation in the Triassic.

Permian younginoids, like Thadeosaurus and Protorosaurus, gave rise to a large terrestrial radiation in the Triassic.

4. Many of the Triassic lepidosauromorphs did not change much into the Jurassic, Cretaceous and later eras.

By contrast, most of the Triassic archosaurmorphs became extinct or evolved into other taxa during later eras.

5. There are a few chronological oddballs, like Lotosaurus, a taxon claimed to come from Early Triassic sediments, but this seems at odds with the evolution of its purported temporal contemporaries and phylogenetic sisters.

Emausaurus added to the large reptile tree

Emausaurus (Haubold 1990, early Jurassic), the primitive thyreophoran ornithischian dinosaur (Fig. 1), was recently added to the taxon list and it nested with Scelidosaurus at the base of the Ornithischia without upsetting the rest of the large reptile family tree.

Figure 1. Emausaurus skull. This taxon nests with the armored basal ornithischian Scelidosaurus.

Figure 1. Emausaurus skull. This taxon nests with the armored basal ornithischian Scelidosaurus.

Emausaurus is interesting because the palpebral bones, common to all ornithischians, virtually contacted the postorbital/postfrontal creating a roof over the eyeball, leaving a virtual fenestra in the posterior remainder of the orbit. Later taxa incorporate the palpebral(s) into the skull itself.

Since Emausaurus nests with Scelidosaurus in the large reptile tree, it is difficult to say at this point which is the more primitive of the two. Additional taxa will be needed for that. It is interesting to note the longest teeth in the dentary of Emausaurus are the anterior ones, where fangs once appeared in the phylogenetic ancestor, Daemonosaurus.

The Archosauria as of today with several new taxa added since last posted.

Figure 2. The Archosauria as of today with several new taxa added since last posted. The addition of Emausaurus does not change the topology of the large reptile family tree. 

The Genasauria
Traditionally the most primitive ornithischians are Pisanosaurus and Heterodontosaurus. Both are considered sisters to all other ornithischians, collectively known as the Genasauria, a clade that traditionally splits into Thyreophora (Lesothosaurus and armored dinos) and Neornithischia (Stormbergia, Agilisaurus, Hexinlusaurus and Cerapoda (duckbills, ceratopsians and pachycelphalosaurs).

No outgroup is known yet for the Ornithischia in traditional trees.

The large reptile tree does not dive deeply into the Dinosauria, but basal forms divide into different divisions with a base on a sister to Daemonosaurus. Unfortunately, this taxon is omitted or ignored in all prior ornithischian studies. In the large reptile tree, the armored dinosaurs (Scelidosaurus and Emausaurus) split off first. Pisanosaurus is a poposaur, so is not as directly related to ornithischians as traditional paleontologists suppose.

I hope other workers will add the taxa listed above to their trees to see if this experiment can be duplicated. M. Mortimer did something similar, but oddly the theropods nested as derived rather than basal in that tree, basically upside-down from the present topology.

Similarly, Lesothosaurus, which is basal in several other trees, nests as derived in this tree, all due to the influence of new outgroups.

References
Haubold H 1990. Ein neuer Dinosaurier (Ornithischia, Thyreophora) aus dem Unteren Jura des nördlichen Mitteleuropa. Revue de Paleobiologie 9(1):149-177. [In German]

Hexinlusaurus, Yinlong and Stenopelix

Earlier we looked at the skull of the basal ornithischian, Hexinlusaurus. Today we’ll look at the post-crania. A reconstruction (Fig. 1) was created by simply putting the original drawings (He and Cai 1983) together to the same scale.

The post-crania of Hexinlusaurus reveals it to be a small-skull taxon with long running legs.

Figure 1. The post-crania of Hexinlusaurus reveals it to be a small-skull taxon with long running legs. A likely biped, the long neck permitted the skull to reach the substrate for water while maintaining a bipedal configuration, but just as easily the forelimbs could have steadied this dinosaur. The wide caudal transverse processes are also found in pachycephalosaurs.

Hexinlusaurus multidens ZDM T6001 (He and Cai 1983, Barrett, Butler and Knoll 2005) middle Jurassic is a long-legged ornithischian with a rather long neck and small skull. Ironically, this is hardly what one would expect at the base of the short-necked, large skull ceratopsians like Yinlong (Figs. 2,3), yet that is where the large reptile tree (dinosaur focus) nests these two. Hexinlusaurus is primitive enough to also be basal to pachycephalosaurs, the thick-headed dinosaurs, long known to share a common ancestor with ceratopsians, and to Ornithopoda, the iguanadontid and duckbill dinosaurs represented here by Dryosaurus.

Figure 2. The skull of Yinlong a basal certatopsian. The marked concavity in the postorbital of Hexinlusaurus is accented in Yinlong.

Figure 2. The skull of Yinlong a basal certatopsian. The marked concavity in the postorbital of Hexinlusaurus is accented in Yinlong.

The marked concavity noted in the postorbital of Hexinlusaurus is accented in Yinlong. The temporal region in Yinlong is larger and longer, probably to house larger jaw muscles working on tougher plant materials. We can suppose that Hexinlusaurus had large premaxillary fangs due to phylogenetic bracketing.

Figure 3. Yinlong overall. This basal ceratopsian had a larger skull, shorter neck and shorter tail than Hexinlusaurus, its phylogenetic predecessor.

Figure 3. Yinlong overall. This basal ceratopsian had a larger skull, shorter neck and shorter tail than Hexinlusaurus, its phylogenetic predecessor. The marked concavity in the postorbital of Hexinlusaurus is accented in Yinlong.

The Stenopelix connection
A skull-less fossil sharing several traits with Yinlong was described by Meyer (1857) and named Stenopelix (Fig. 4). Yes, they do look quite similar, don’t they?

Figur 4. Known since 1857, Stenopelix appears to be a sister to Yinlong. Ischia are color coded here.

Figur 4. Known since 1857, Stenopelix (Meyer 1857) appears to be a sister to Yinlong. Ischia are color coded here. Click to enlarge.

References
Barrett PM, Butler RJ and Knoll F 2005. Small-bodied ornithischian dinosaurs from the Middle Jurassic of Sichuan, China. Journal of Vertebrate Paleontology 25: 823-834.
He X-L and Cai K-J 1983. A new species of Yandusaurus (hypsilophodont dinosaur) from the Middle Jurassic of Dashanpu, Zigong, Sichuan. Journal of Chengdu College of Geology, Supplement 1:5-14.
Meyer H von 1857. Beiträge zur näheren Kenntis fossiler Reptilien. Neues Jahrbuch für Mineralogie, Geologie und Paläontologie 1857: 532–543.
Xu X, Forster CA, Clark J M and Mo J 2006. A basal ceratopsian with transitional features from the Late Jurassic of northwestern China. Proceedings of the Royal Society B: Biological Sciences. First Cite Early Online Publishing. online pdf

Poposaurs to scale and the chronological Lotosaurus problem

Updated April 22, 2014 to reflect the new basal archosaur position of poposaurids.

Adding Sacisaurus (Fig. 1) as a basal member of the poposaur list adds a certain perspective.  It calls into question the early Triassic appearance of Lotosaurus (Fig.1) since all other poposaurs are Late Triassic. Either the geological setting for Lotosaurus was poorly calibrated, or these poposaurs all had a much earlier origin, in the Permian, which appears unlikely. The other possibility is that Lotosaurus is not a poposaur after all, but an offshoot of another Permian root. This might be interesting…

Poposaurs now nest as basal archosaurs. So the chronology problem goes away.

Figure 1. Poposaurs to scale and in phylogenetic order (top to bottom). Sacisaurus is at the base. Silesaurus and Lotosaurus are derived. Poposaurus is one of the largest, along with Lotosaurus.

Figure 1. Poposaurs to scale and in phylogenetic order (top to bottom). Sacisaurus is at the base. Silesaurus and Lotosaurus are derived. Poposaurus is one of the largest, along with Lotosaurus. Pisanosaurus, basal ornithischian, does not belong in this clade.

Cynodontipus – a “hairy paw” from the Middle Triassic?

Dr. Paul Ellenberger will go down in history for his work on Cosesaurus, but his passion was fossil footprints. One impression he considered was this purported “hairy paw” from the Middle Triassic of France. Ellenberger (1976) named it Cynodontipus (Fig. 1). Each “toe” was about 2 inches (5 cm) in width.

Cynodontipus in situ, a partial hairy paw print.

Figure 1. Cynodontipus in situ, a partial purported hairy paw print. This is an excellent print, but difficult to interpret. The hair seems misplaced and anachronistic. The wide toes are odd. So is the lack of ungual imprints.

Ellenberger (1976) interpreted his fossil this way (Fig. 2).

Ellenberger's interpretation of Cynodontipus.

Figure 2. Ellenberger’s interpretation of Cynodontipus.

Hairy pads are not known even in modern arctic mammals, so why should we expect hairy pads in Triassic cynodonts? Especially when one can’t differentiate the pads?? There’s no match for this foot among known Triassic taxa. Perhaps there is another explanation for this enigma.

 

Figure 3. Cynodontipus burrows, likely from a procolophonid. Each color represents a new burrow direction from a central origin.

Figure 3. Cynodontipus burrows, likely from a procolophonid. Each color represents a new burrow direction from a central origin.

So what is it?
When we consider the “hair,” we are drawn to the therapsids as possible candidates, as Ellenberger surmised. But this fossil demonstrates way more hair than can be expected at such an early date. Even in mammals the hands and feet are the last parts to get hairy, and usually pads are plain to see, so this fossil just doesn’t fit several typical ichnite patterns.

Luckily there’s Olsen’s 2012 take on it.
Olsen 2012 wrote: In addition to its type locality in the Middle Triassic of France, Cynodontipus has been identified from the Middle Triassic of Germany, the Middle and Late Triassic of Morocco, the Late Triassic of Nova Scotia, Canada, and the Late Triassic of Connecticut, USA. This last occurrence consists of unlabeled part and counterpart slabs discovered in the Hitchcock collection at the Beneski Museum of Natural History at Amherst College. These specimens show that Cynodontipus is a vertebrate burrow that terminates at a recalcitrant subsurface bedding interface and is not a footprint. The simplest hypothesis of the trace maker of Cynodontipus is that it was a produced by burrowing procolophonids, which are know from the same deposits, are the right size, and are known to have burrowed.

Thus the lines that Ellenberger considered hairs must be tunnel scratch marks instead. Doesn’t that make more sense?

The key take away on this
Even experts can have different opinions on the same fossil. More data appears to clarify enigmas. That’s the progress of Science and that’s what makes this paleo study so fascinating. No one need vilify Ellenberger for his misinterpretation. Likewise, no one need denigrate the results published in reptileevolution.com or here at pterosaurheresies, even if and when results are shown to be in error. Errors need to be corrected, but never by blackwashing an entire output. DN and MW, I hope you’re listening. Olsen (2012) handled Ellenberger’s error very well indeed. We should all take note. Be specific and back up your corrections with evidence.

References
Ellenberger P 1976. Une piste avec traces de soies épaisses dans le Trias inférieur a moyen de Lodéve (Hérault, France): Cynodontipus poythrix nov. gen. nov. sp. les cynodontes in France. Géobios 9(6)769-787.
Olsen PE. 2012.
Cynodontipus: A procolophonid burrow – not a hairy cynodont track (Middle-Late Triassic: Europe, Morocco, Eastern North America. Geological Society of America Abstracts with Programs, Vol. 44, No. 2, p. 92.
Olsen PE, Et-Touhami, M, Whiteside, JH, 2013 (in prep). Cynodontipus Ellenberger is a vertebrate burrow, not a hairy synapsid track. for Journal of Vertebrate Paleontology.