Pangupterus: a juvenile Moganopterus

Lü et al. 2016
described a new tiny, long-snouthed pterosaur, Pangupterus liui (Jiufotang Fm., Liaoning, Aptian, Early Cretaceous; Figs. 1, 2). Lü et al. thought they had a mandible with a 30º divergence at the jaw symphysis 1/5 of the total jaw length (Fig. 1).

But then, they also report,
“The distal end of the rostrum is slightly expanded, and although it has been destroyed, it seems to have a bony process in the middle, which is similar to the case in Longchengopterus.” The paper has several authors. I don’t think they read each others input.

The color illustration of a restored Pangupterus
that was included with the paper does not follow the first description, but features extremely narrow jaws closer to the second description. The restored body was imaginatively based on a Pterodactylus bauplan.

Figure 1. Pangupterus in situ. Lü et al. had first hand access and considered this a mandible with a symphysis at 1/5 the jaw length. Here, based on this photo,  it is interpreted as a rostrum and mandible, both with parallel rami. If you’re looking at this on a 72 dpi monitor the image is 7/5 larger than life size.

Here, based on tracing
the photo in figure 1, a narrow rostrum lies at an angle to the equally narrow mandible. And the resulting reconstruction matches that of only one pterosaur, Moganopterus, except for its size. The skull of Pangupterus is only 1/4 as long as in Moganopterus (Fig. 2). A hatchling Monganoterpus, if it followed the pattern of other pterosaur hatchlings, would have been 1/8 the size of the adult (Fig. 2) or half the size of Pangupterus.

Figure 2. No other pterosaur has such narrow jaws tipped with slender teeth. Pangupterus is a good candidate to be a juvenile Moganopterus, as shown here.

Moganopterus zhuiana 41HIII0419 (Lü et al. 2012) Early Cretaceous was a large sister to Feilongus and the cycnorhamphids. The skull was extraordinarly stretched out. Feeble needle-like teeth lined the anterior jaws. A long crest that did not break the rostral margin appeared posteriorly. And the neck vertebrae were very much elongated. Likely this was a very tall pterosaur.

Several other blog spots
covered Pangupterus. Some reimagine it as a hummingbird-like specimen. See other images here, here, here and here.

This specimen
further confirms the presence of tiny, long-snouted pterosaurs, some of them juveniles of larger long-snouted pterosaurs, and the isometric ontogenetic growth of all pterosaurs.

References
Lü J-C, Pu H-Y, Xu i, WuY-H and Wei X-F 2012. Largest Toothed Pterosaur Skull from the Early Cretaceous Yixian Formation of Western Liaoning, China, with Comments On the Family Boreopteridae. Acta Geologica Sinica 86 (2): 287-293.
Lü J-C, Liu C, Pan L-J and Shen C-Z 2016. A new pterodactyloid pterosaur from the Early Cretaceous of the Western part of the Liaoning Province, Northeastern China. Acta Geologica Sinica (English) 90(3):777-782.

wiki/Moganopterus
/wiki/Pangupterus

Another look at the tiny pterosaur, Nemicolopterus

Not content
with a fully resolved cladogram, I wanted higher Bootstrap scores at certain nodes to ascertain nesting pairs. So I reviewed the data for several taxa, among them Nemicolopterus. I found mistakes and oversights, nearly all of which more closely match Nemicolopterus to its much taller sister, Shenzhoupterus (Fig. 1) within the larger encompassing Germanodactylus/Tapejara clade.

Figure 1. Germanodactylus cristatus and members of the Shenzhoupteridae, Nemicolopterus and Shenzhoupterus.

When first announced
(Wang et al. 2008), Nemicolopterus was hailed as the smallest, or one of the smallest known pterosaurs. And it is. But there is one other that is only half as tall (Fig. 2) which we looked at in more detail yesterday, B St 1967 I 276.

Figure 2. Nemicolopterus has been described as the smallest pterosaur, but B St 1967 I 276, No. 6 in the Wellnhofer (1970) catalog was only half as tall.

An insitu tracing 
animated in a GIF movie reveals the bones segregated by digital layers (Fig. 3).

Figure 3. Two images of Nemicolopterus superimposed and traced with transparent colors. Note, not all of the shapes seen in photo 1 can be seen in photo 2. There appear to be extra tiny bones in the belly of this specimen where all the ribs and gastralia have been accounted for. Click to enlarge. 

A displaced sliver of bone in the cheek
would appear to be the ventral portion of an orbit-dividing lacrimal, as in sister taxa. No one would identify this bone as such without phylogenetic bracketing. Hairlike soft tissue arising from the rostrum evidently precedes the rostral crest found in Shenzhoupterus. The free fingers remain unknown.

Phylogenetic miniaturization 
appears to be at work once again with Nemicolopterus, a tiny adult at the base of a major clade or two of pterosaurs in the large pterosaur tree.

References
Wang X, Kellner AWA, Zhou Z and Campos DA 2008. Discovery of a rare arboreal forest-dwelling flying reptile (Pterosauria, Pterodactyloidea) from China. Proceedings of the National Academy of Sciences, 106(6): 1983–1987. doi:10.1073/pnas.0707728105

wiki/Nemicolopterus

Pregnant hummingbird-like pterosaurs

Earlier
here and here we looked at pregnant pterosaurs. As you may recall, as lepidosaurs pterosaurs could retain their young in utero much longer than archosaurs do. Archosaur embryos are microscopic when laid and they develop in the egg outside of the uterus. Some extant lepidosaurs retain their young in utero to the stage of viviparity. Others lay eggs at an advanced stage. Today, two more tiny pterosaurs are shown to be adult females, based on the embryo inside of each of them.

As long-time readers know, 
phylogenetic analysis of the Pterosauria that includes the tiniest hummingbird-sized individuals from the Solnhofen formation nest them all as adults. They have been phylogenetically miniaturized and generally they nest at the bases of major clades. Generally the smallest pterosaurs are transitional from larger taxa and to larger taxa, but they are also often surrounded by other tiny transitional pterosaurs. That’s how we arrive at pterodactyloid-grade pterosaurs at least 4x. By convergence anurognathids and wukongopterids also added some, but not all, pterodactyloid traits.

Other workers,
who refuse to test the tiny ones, mistakenly assert that the tiny ones are babies. If that were true then, as the other workers suggest, pterosaurs would have to develop isometrically, changing shape with maturity. Several examples of embryo and juvenile pterosaurs demonstrate irrevocably that that is not true. Juveniles and embryos are carbon copies of the adults.

The smallest adult pterosaur is
Pterodactylus? kochi? B St 1967 I 276 (No. 6 of Wellnhofer 1970, (Figs. 1,2).

Figure 1. Pterodactylus? kochi? B St 1967 I 276 (No. 6 of Wellnhofer 1970) is the smallest known adult pterosaur. It is also pregnant. Note the relatively enormous sternal complex, analogous to that of a hummingbird of similar size.

I did not realize
how large the sternal complex was on this pterosaur, Such a large pectoral anchor suggests the wings were flapped strongly or rapidly or both, possibly as in similarly-sized hummingbirds. The coracoids are also larger than earlier reconstructed.

Figure 2. The torso of B St 1967 I 276 (No. 6 of Wellnhofer 1970) showing elements of the pectoral girdle, pelvic girdle and embryo. The coracoids are also quite large. 

Nesting with the smallest known pterosaur
in the large pterosaur cladogram, is another tiny Solnhofen specimen, BMNH 42736, which also has a large sternal complex and is, by coincidence, pregnant.

Figure 4. Two of the smallest pterosaurs that both have a large sternal complex. BMNH42736 and B St 1967 I 276. If your screen resolution is 72 dpi, these are shown > 1.5x larger than they were in life.

All I really wanted to do
was gather the data on this pterosaur to see where mistakes had been made. Finding tiny extra bones in the base of the abdomen was a surprise. These two, despite their differences, nest together in the large pterosaur tree.

Figure 6. BMNH 42736 showing various bones, soft tissues and embryo.

References
Bennett SC 2006. Juvenile specimens of the pterosaur Germanodactylus cristatus, with a review of the genus. Journal of Vertebrate Paleontology 26:872–878.SMNS
Hedges SB and Thomas R 2001. At the Lower Size Limit in Amniote Vertebrates: A New Diminutive Lizard from the West Indies. Caribbean Journal of Science 37:168–173.
Hone and Benton 2006. Cope’s Rule in the Pterosauria, and differing perceptions of Cope’s Rule at different taxonomic levels. Journal of Evolutionary Biology 20(3): 1164–1170. doi: 10.1111/j.1420-9101.2006.01284.x
Unwin D M 2006. The Pterosaurs From Deep Time. 347 pp. New York, Pi Press.
Wang X, Kellner AWA, Zhou Z and Campos DA 2008. Discovery of a rare arboreal forest-dwelling flying reptile (Pterosauria, Pterodactyloidea) from China. Proceedings of the National Academy of Sciences, 106(6): 1983–1987. doi:10.1073/pnas.0707728105
Wellnhofer P 1970. Die Pterodactyloidea (Pterosauria) der Oberjura-Plattenkalke Süddeutschlands. Abhandlungen der Bayerischen Akademie der Wissenschaften, N.F., Munich 141: 1-133.

wiki/Pterodactylus

 

 

Another look at the smallest adult pterosaur – AND its hatchling

Earlier we looked at the smallest adult pterosaur, B St 1967 I 276 or No. 6 in the Wellnhofer (1970) catalog. Here (Fig. 1) it is compared to an adult leaf chameleon, Brookesia micro, one of the smallest living lizards and to the Bee hummingbird, one of the smallest living birds. Also shown are their hatchlings and eggs.

Figure 1. The smallest of all adult pterosaurs, B St 1967 I 276 or No. 6 in the Wellnhofer (1970) catalog compared to scale with the living leaf chameleon (Brookesia micro) sitting on someone’s thumb. Also shown are hypothetical eggs and hatchlings for both. These lepidosaurs had tiny eggs and hatchlings, relatively larger in the chameleon, based on pelvis size and average 1/8 size for other pterosaur hatchlings.

 

Traditional paleontologists
don’t buy the argument that No. 6 was an adult, even though it is much larger than the smallest lizard and about the size of the smallest bird. Worse yet, they refused to test it in phylogenetic analysis. So, the  impasse remains.

Figure 2. Smallest known bird, Bee hummingbird, compared to smallest known adult pterosaur, No. 6 (Wellnhofer 1970). Traditional workers consider this a hatchling or juvenile, but in phylogenetic analysis it does not nest with any 8x larger adults. This image is slightly larger than life size at 72dpi. Note the much smaller eggs produced by the tiny pterosaur. 

 

Pictures tell the tale.
You can see for yourself. No. 6 is substantially smaller than other tiny pterosaurs just as the bee hummingbird is substantially smaller than other hummingbirds.The hatchling was substantially smaller than both the leaf chameleon and bee hummingbird hatchlings based on their larger egg size/pelvis opening.

Earlier we looked at isometric growth in several pterosaurs, with hatchlings matching adults in morphology. Earlier we also took note of the danger of desiccation to hatchling pterosaurs until they reached a certain size/volume, so they probably roamed the leaf litter, which is probably when pterosaurs became quadrupeds and developed elongate metacarpals 4x.

References
Hedges SB and Thomas R 2001. At the Lower Size Limit in Amniote Vertebrates: A New Diminutive Lizard from the West Indies. Caribbean Journal of Science 37:168–173.
Wellnhofer P 1970. Die Pterodactyloidea (Pterosauria) der Oberjura-Plattenkalke Süddeutschlands. Abhandlungen der Bayerischen Akademie der Wissenschaften, N.F., Munich 141: 1-133.

wiki/Pterodactylus

A new(?) tiny “pterodactyloid” (from 1841!) with a short neck

Figure 1. Tiny Pterodactylus? pulchellus (=micronyx) from the Natural History Museum London. Some DGS has been applied to bring out certain details. If your screen resolution is 72 dpi, then you’re seeing this fossil full size.

In the new book, Pterosaurs (Witton 2013:198), a tiny pterosaur with a 3 cm long skull with a long rostrum was pictured (Fig. 1). Witton identified the tiny pterosaur as a juvenile in the Natural History Museum London collection. After process of elimination, I’m guessing this is a Solnhofen (Late Jurassic) specimen PV R 2721 attributed by Meyer (1841) to Pterodactylus puchellus. [I could be wrong.] Later workers called it P. micronyx. I don’t know the Wellnhofer (1970) number.

Here it is at full scale (Fig. 1, if your screen is set to 72dpi). The inset shows the pes reconstructed. The pes alone with its long metatarsal 1 identifies it as a descendant of the scaphognathids (Peters 2011). Phylogenetic analysis nested it between another tiny pterosaur (but slightly larger) with a shorter rostrum, GMU-10157 (Fig. 2) and Cycnorhamphus (Fig. 3) a much larger specimen.

Notice the resemblance? 

Figure 2. GMU-10157 (above) and (I think) the Meyer 1841 specimen PV R 2721 (below) to the same scale. The Meyer specimen is slightly smaller overall, yet has a longer rostrum and nests at the base of the Cycnorhamphus clade. GMU-10157 nests at the base of the cycnorhamphids + ornithocheirids.

The interesting thing…
The Meyer 1841 specimen is actually smaller than GMU-1-157, and yet it has a longer rostrum! That breaks one of the “rules” under the old allometric ontogenetic growth paradigm. Here these two tiny adults are part of a long gradual evolutionary continuum of size reduction and enlargement (Fig. 3). And this, ladies and gentlemen, is how you evolve a Cycnorhamphus. It’s the closest known outgroup taxon. Further out GMU-10157 nests at the base of the cycnorhamphids + ornithocheirids.

Figure 3. Cycnorhamphus, its sisters and predecessor taxa, sans the Meyer 1841 specimen.

Witton (2013) considered Cycnorhamphus a ctenochasmatoid, related to Pterodactylus and Ctenochasma. They’re not related according to the results of the large pterosaur family tree (where the Meyer specimen will shortly be added). You have to go back to Dorygnathus to find a last common ancestor. If you eliminate Ctenochasma then Scaphognathus is the last common ancestor. Obviously, given the generic name Meyer (1841) applied to this specimen, this sort of mistake has been going on for a long, long time.

Figure 4. Reconstruction of the tiny London specimen, shown larger than actual size. Derived from a sister to the GMU specimen (Fig. 2), the London specimen was ancestral to cycnhorhamphids. A great pes subdivided by PIL (parallel interphalangeal lines). You can even see the very beginnings of that dentary bend that reaches its acme in the bent-jaw cyc (Fig. 3). But no long legs yet.

The short neck problem
Darwinopterus was promoted as a transitional pterosaur, having the long rostrum and long neck of a pterodactyloid, but the remainder of the body with its long tail and long toe 5 were pre-pterodactyloid. The Meyer specimen, along with others, then presents a problem. It has a short neck and, for that matter, a shorter rostrum than Darwinopterus. GMU 1-157 has an even shorter rostrum. TM-13104 (Fig. 3) has an even shorter rostrum and longer metacarpals, yet it nests as a descendant of Scaphognathus.

Expectations and reality all fall apart rather quickly if you hang your hat on Darwinopterus, a specimen that is a “dead end” taxon in the large pterosaur family tree. Expand the gamut in your taxon list and see what new relationships emerge.

No such problems here.
If you don’t believe me that this is a tiny adult in the lineage of cycnorhamphids, just add it to your own analysis. Repeating the test is good Science. Throwing insults from the sidelines is not, unless they come with good evidence in tow. It is also possible that this specimen is young. Without an eggshell beside it, the tiny pterosaurs give few clues as to their ontogenetic age, other than their phylogenetic nestings and the sizes of their sisters. Here the sizes vary considerably.

Pterosaur workers have been avoiding tiny pterosaurs, denigrating them as pre-morph juveniles, when tiny pterosaurs hold the key to understanding pterosaur relations. Similarly pterosaur workers have been avoiding tritosaur/fenestrasaur/lepidosaurs, when they hold the key to pterosaur origins.

Take a good look at that skull
With that long concave rostrum, procumbent anterior teeth and pelvis shape in the Meyer specimen, we’re getting very close to the morphology of Cycnorhamphus. There’s no fronal/parietal crest yet. The long neck, long legs and longer metacarpals were yet to come. The free fingers were likewise getting close in proportion to one another.

If this is not the Meyer 1841 specimen,  PV R 2721, please let me know to make the correction.

References
Witton M. 2013. Pterosaurs. Princeton University Press. 291 pages.

Tiny pterosaurs – breaking the short rostrum false paradigm

With the false paradigm still in force among professional paleontologists that juvenile pterosaurs all have a short rostrum and a large orbit (Witton 2013 and references therein, like birds and crocs and mammals), it’s worthwhile to take a look at several tiny pterosaurs, each with a long rostrum. Each has been nested phylogenetically in the large pterosaur tree, the only effort, so far, to nest the tiny ignored ones. 

Here are nine tiny taxa, each with a fairly long – to extremely long – rostrum
Seven are found without an eggshell present (Figs. 1-7). Whether these are hatchlings, juveniles or adults cannot be determined except by their phylogenetic nesting. If sister taxa are large, then it’s more likely that these are juveniles. However, 1-7 are all surrounded by or nest next to tiny taxa. They also all nest after a series of larger taxa and prior to another series of larger taxa that all establish new clades. This is how pterosaurs evolved new clades.

Two others are embryos surrounded by eggshells (Figs. 8-9). Both of these are phylogenetically surrounded by large taxa.

Figure 1. ?Pterodactylus spectabilis, TM10341, n1 in the Wellnhofer 1970 catalog. This is no Pterodactylus, but a tiny dorygnathid. Click to learn more.

TM 10341 nests between a much larger Dorygnathus (SMNS 50164) and slightly larger “Rhamphodactylus“ BSPG 2011 I 133.

Figure 2. BSp 1968 XV 132 nests with Cycnorhamphids and tiny scaphognathids. Click to learn more.

BSp 1968 XV 132 nests between the smaller GMU 10157 and the equally small, BSt 1936-I-50 no. 30 (Fig. 3), close to cycnorhamphids.

Figure 3. B-St-1936-I-50 no. 30. Click to learn more.

BSt 1936 I 50 (no. 30 in the Wellnhofer 1970 catalog) nests with BSp 1968 XV 132 (Fig. 2).

Figure 4. MB.R.3530.1-(No.40) basal to ctenochasmatids

MB.R.3530.1 (No.40) nests between the equally tiny St/Ei I (derived from the larger Angustinaripterus) and ?Ctenochasma elegans (AMNH 5147, Fig. 5).

Figure 5. AMNH 5147, basal to ctenochasmatids

AMNH 5147 nests between tiny MB.R.3530.1 (Fig. 4) and larger Gnathosaurus.

Figure 6. Pterodactylus? elegans? BSPG 1911 I 31 (no. 42 in the Wellnhofer 1970 catalog). Click to learn more. Basal to azhdarchids, distantly derived from no. 1 (Fig 1.)

BSPG 1911 I 31 (no. 42 in the Wellnhofer 1970 catalog) nests between CM 11426 (no. 44 in the Wellnhofer 1970 catalog) and Sos 2428, the flightless pterosaur on one branch and the pro to-azhdarchid, Jidapterus, on the other branch.

Figure 7. Senckenberg-Museum Frankfurt a. M. No. 4072. Click to learn more.

Senckenberg-Museum Frankfurt a. M. No. 4072 (no. 12 in the Wellnhofer 1970 catalog) nests between the smallest pterosaur, B St 1967 I 276 (No. 6 of Wellnhofer 1970) and a larger specimen, B St ASXIX 3 (plate) SMF No. R 404 (counterplate), No. 23 of Wellnhofer 1970). No. 6 had a smaller snout and larger rostrum because it was more closely related to tiny Ornithocephalus and the larger Scaphognathus (no. 110), and the even larger Scaphognathus (no. 109). See all of these in one image here.

And now, the embryos:

Figure 8. JZMP-03-03-2 embryo shown with hypothetical 8x larger adult and sister taxa scaled to the adult. Click to learn more and see detailed imagery of the embryo in the eggshell.

Misinterpreted as a Beipiaopterus, the embryo JZMP-03-03-2 nests between the basal ornithocheirids, Yixianopterus and Haopterus (Fig. 8). An adult of the embryo would be twice the size of Haopterus.  

Figure 9. Pterodaustro embryo. There certainly is no short snout/large eye here! However there are several differences between this specimen and the adult. Click to learn more.

The Pterodaustro embryo nests with its parent, Pterodaustro and this lineage disappears after this taxon. There are slight differences between the embryo and adult Pterodaustro. There are differences between adult Pterodaustro, detailed here.

Certainly there are embryos and tiny pterosaurs with a short rostrum and large orbit (like the IVPP embryo which is the size of other adult anurognathids!). All sister taxa likewise have a short rostrum and large orbit and other similar traits detailed here.

Earlier we looked at a hypothetical Quetzalcoatlus sp. embryo tucked into a long shell to accommodate that long rostrum. Pterodaustro likewise produced an elongated egg to accommodate that hyperelongated rostrum.

References
Click to each taxon for additional references.