A Pterosaur Without Limbs and Where to Find Them

BML-37012 (No. 85 in the Wellnhofer 1975 catalog) was considered to be a juvenile Rhamphorhynchus preserved largely without limbs (one femur listed). This small specimen (skull length: 2.8 cm) was also presented in Wellnhofer’s (1991) Encyclopedia of Pterosaurs. It appears to be unprepared.

BML-37012 (n45 in the Wellnhofer 1975 catalog) is a small and primitive Rhamphorhynchus

Figure 1. BML-37012 (n85 in the Wellnhofer 1975 catalog) is a small and primitive Rhamphorhynchus, phylogenetically close to the BMM specimen. Above: the in situ specimen, apparently without limbs. Below: A DGS tracing indicating where to dig for the limbs. Blanketing layers of Solnhofen limestone indicate where one will find more bone slightly beneath the surface. Determining where fossils may be just below the surface  by looking for bumps in the matrix is an age-old technique used by fossil preparators. Image from Wellnhofer 1991. Enlargements and overlays available by request. 

Solnhofen Preservation
When a fossil specimen is discovered by splitting Solnhofen limestones, typically many bones remain invisible, hidden beneath a thin blanket of limestone at the separation layer. Preparators can usually create a precise outline of the specimen, even when the bones are rather deep, because preparators can see the general direction of the fossil (head on one end, tail on the other) and the exact location of other elements are often betrayed by a slight rise in the matrix. Like a blanket over a child in bed, the limestone tells you exactly where to dig.

DGS Preview
The Digital Graphic Segregation (DGS) method permits an increase in contrast in the image of the matrix surrounding the fossil. This better indicates where the bumps and valleys are in the limestone blanketing the fossil. Doing so I was able to trace a complete and largely articulated forelimb disarticulated from the rest of the fossil and a complete hindlimb tucked close to the body. Another tibia and pedal digit 4 is twisted and tucked in behind the lumbar region of the fossil, visible without DGS. This particular tibia may be the previously identified femur. Pedal digit 4 was closely aligned with the deeper ilium and so was overlooked. While others dismiss and decry this method using Adobe Photoshop, it is exactly what preparators have been doing by eye for generations.

 

Figure 2. Reconstruction of Rhamphorhynchus specimen BML-37012 (n85 of Wellnhofer 1975).

Figure 2. Reconstruction of Rhamphorhynchus specimen BML-37012 (n85 of Wellnhofer 1975).

Reconstruction
A digital reconstruction of the fossil looks much like other similar Rhamphorhynchus specimens, like the BMM specimen and B St 1959 I 400 (n10 in the Wellnhofer 1975 catalog). Making such comparisons is one test that confirms the identification of the bones viewed through the blanketing limestone. It would also be a good test of the method if someone with the proper tools dug into the limestone to find the bones beneath the surface.

Description and Distinctions
The BML specimen has larger fingers 1-3 and very large eyes. So was it nocturnal? Did it compete with similarly built and sized anurognathids? Interesting questions that haven’t been brought up before under the false paradigm that such short-snouted rhamphs were simply juveniles of larger specimens. Smaller rhamphs have been dismissed as juveniles, but phylogenetic analysis does not match them to older adults. Rather it finds the small ones were related to each other. I know of no Rhamphorhynchus specimens that are identical to adults only smaller, as in Pterodaustro and PteranodonIf you know of any, please send the data.

Juvenile or Not?
As we learned earlier, hatchling pterosaurs, like juvenile tritosaur lizards in general, are virtual matches to adults. Phylogenetically smaller pterosaurs (those with larger ancestors) generally had a smaller rostrum and larger eyes because they developed in a shorter time in smaller eggs, thus retaining these more embryonic traits as hatchlings and adults. Later, as their descendants increased in utero development time, egg size increased and jaw length generally increased relative to overall size. This specimen, No. 85, matches sister taxa in morphology and is part of an uninterrupted size continuum and so it may be considered an adult. Hatchlings would have been one-eighth the size according to pelvic opening size.

References
Wellnhofer P 1975a. Teil I. Die Rhamphorhynchoidea (Pterosauria) der Oberjura-Plattenkalke Süddeutschlands. Allgemeine Skelettmorphologie. – Paleontographica A 148: 1-33.
1975b. Teil II. Systematische Beschreibung. – Paleontographica A 148: 132-186.
1975c. Teil III. Paläokolgie und Stammesgeschichte. – Palaeontographica 149: 1-30.
Wellnhofer P 1991. The Illustrated Encyclopedia of Pterosaurs. London, Salamander Books, Limited: 1-192.

Evolution of the Pterosaur Palate – part 3 the Campylognathoidea

Earlier we looked at the evolution of the pterosaur palate from pre-pterosaurs to basal pterosaurs and from Dimorphodon to the Anurognathidae. Today we’ll look at the next clade: EudimorphdonCampylognathoides + Rhamphorhynchus. Surprisingly, for as many Rhamphorhynchus specimens that are known, too few preserve an exposed palate. If you have any, please send them!

Evolution of the pterosaur palate from Eudimorphodon to Rhamphorhynchus.

Figure 1. Click to enlarge. Evolution of the pterosaur palate from Eudimorphodon to Rhamphorhynchus.

Trends in the Eudimorphodontidae
Eudimorphodon cromptonellus was overall smaller than E. ranzii, but that didn’t seem to matter much in the morphology (Fig. 1).

Campylognathoides  (SMNS 11879) had greatly enlarged eyes, which is reflected in the posterior expansion and anterior narrowing of the palate and a reduction and narrowing of the ectopalatine.

Campylognathoides (CM 11424) likewise has a narrow ectopalatine, but more robust.

The most basal Rhamphorhynchus, No. 28 in the Wellnhofer (1975) catalog, was a sister to Campylognathoides (CM11424) and this is reflected in the palate, which is identical, but shorter and wider.

The second most basal Rhamphorhynchus, the BMM specimen, was smaller than No. 28 and the proportions of the palatal elements were shorter still. The premaxilla was not pointed at all, but was transverse in orientation, more like an anurognathid. A big change in the pterygoid produced an enlarged pterygoid with a new lateral process and contact with the jugal.

In the two more derived Rhamphorhynchus palates, No. 55 and No. 89 in the Wellnhofer (1975) catalog (Fig. 1), the premaxilla became pointed again, the pterygoid was not so large and the lateral process of the pterygoid becomes longer. The quadrates had a greater angle of posterior lean and this is reflected in seeing their posterior aspects becoming increasingly ventral.

Here the phylogenetic size reduction led to a more embryonic short snout. The succeeding phylogenetic size enlargement (with longer embryonic development) led to a longer snout.

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
Wellnhofer P 1975a-c. Teil I. Die Rhamphorhynchoidea (Pterosauria) der Oberjura-Plattenkalke Süddeutschlands. Allgemeine Skelettmorphologie. Paleontographica A 148: 1-33.Teil II. Systematische Beschreibung. Paleontographica A 148: 132-186. Teil III. Paläokolgie und Stammesgeschichte. Palaeontographica 149: 1-30.

wiki/Rhamphorhynchus

New Rhamphorhynchus + Fish Fossil: Exceptionally Beautiful!

One of the most beautiful and spectacular pterosaur fossils I have ever seen has just been unveiled. Frey and Tischlinger (2012) describes a Rhamphorhynchus (WDC CSG 255) with its belly full of fish and its throat stuffed with a recently swallowed fish entangled with a larger fish, Aspidorhynchus.

Wow! Rare! Gorgeous! Spectacular! …and that’s only the start for this exciting fossil.

[PterosaurHeresies.com will always go the extra mile – with evidence.]

Rhamphorhynchus entangled with Aspidorhynchus

Figure 1. Rhamphorhynchus entangled with Aspidorhynchus. Both complete and articulated. Inside the belly of Rhamphorhynchus are several smaller fish. Inside its throat is another. Image from Frey and Tischlinger (2012). You can see the five smaller slabs that were reattached to one another to recreated the entire slab.

The Scene Frozen in Time
Frey and Tishclinger (2012) report, “Rhamphorhynchus was seized during or immediately after a successful hunt.” Both specimens died during the encounter and sank together to bottom of the lagoon where they were preserved intact in Solhnfofen limestones. Stomach contents from this and other Aspidorhynchus specimens have never revealed pterosaur contents, so this encounter may have been more out of idle curiosity on the part of the fish. The authors report, “The fish tail yet sticking in the pharyngeal region of the throat and the excellent preservation of the tiny fish without any trace of digestion suggests that swallowing was not completed and that the Rhamphorhynchus was alive and airborne during the attack. 

‘The Aspidorhynchus apparently attacked from in front when the Rhamphorhynchus still flew low above water surface, grabbed the left wing level with the distal end of the antebrachium close to the carpus and pulled the pterosaur under water. 

‘Obviously, the fish was neither able to swallow the pterosaur, neither was it able to get rid of its oversized victim.”

Skimming pterosaur

Figure 2. Manipulating the bones of the fish-eating Rhamphorhynchus into a skimming configuration while staying airborne. The bent hyoid appears as if it could have acted like a stop to prevent the lower jaw from opening too far due to hydrodynamic drag while skimming. The long, sharp, anteriorly-oriented teeth have long been considered ideal for fish trapping.

Skimming
Frey and Tischlinger (2012) report, “The specimen presented here firstly proves evidence that the Late Jurassic pterosaurs of the genus Rhamphorhynchus actively hunted fish by grabbing or skimming them out of the water thereby closely approaching the water surface due to their short necks.”  The bent hyoid (Fig. 2) appears as if it could have acted like a stop to prevent the jaw from opening too widely due to hydrodynamic drag while skimming.

A selection of Rhamphorhynchus feet

Figure 3. Click to enlarge. A selection of Rhamphorhynchus feet compared to the new one associated with a large fish. Note the morphological differences exhibited by the new specimen, WDC CSG 255 (far right). Note the brevity of pedal digit 5, the relative lengths of the metatarsals and the relative lengths of the phalanges, especially p3.2. Despite the differences with these eight other rhamps, the PILs (parallel interphalangeal lines) in the WDC specimen are all continuous.

Interesting Tidbits
The foot of this specimen (WDC CSG 255 – Fig. 3) did not match the feet of other Rhamphorhynchus specimens, which also did not match each other. The differences are subtle, yet suggest speciation within this genus, despite the apparent overall match (which has yet to be compared with reconstructions) to the darkwing specimen of R. muensteri.

Close-Ups 
Closeup photos of the wingtips and metacarpus were requested, but none have been forthcoming. Such a complete specimen should show wing tip unguals and a vestigial manual digit 5, which tentatively appear in the present photographs. The pedal 5 ungual is present (Fig. 2), a bone typically overlooked in all other pterosaurs, but present nevertheless (Peters 2011).

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
Frey E and Tischlinger H (2012). The Late Jurassic Pterosaur Rhamphorhynchus, a Frequent Victim of the Ganoid Fish Aspidorhynchus? PLoS ONE 7(3): e31945. doi:10.1371/journal.pone.0031945, available online
Peters D 2011. A Catalog of Pterosaur Pedes for Trackmaker Identification Ichnos 18(2):114-141. http://dx.doi.org/10.1080/10420940.2011.573605

WDC = Wyoming Dinosaur Center (WDC), Thermopolis, U.S.A.

What is Qinglongopterus? Perhaps a Junior Synonym.

Lü et al. (2012) erected a new genus and species for a new rhamphorhynchid from the Tiaojishan Formation of China (Mid/Late Jurassic). They reported, “Qinglongopterus is strikingly similar to Rhamphorhynchus and more closely related to this taxon than to any other rhamphorhynchine.”

 

Figure 1. Qinglongopterus? guoi. A new Rhamphorhynchus species. Tracing of photo of specimen modified with wings and leg out, skull reconstructed, sternum flipped.

Figure 1. Qinglongopterus? guoi. A new Rhamphorhynchus species. Tracing of photo of specimen modified with wings and leg out, skull reconstructed, sternum flipped.

Ontogeny
Lü et al. (2012) considered the Qinglongopterus specimen immature due to lack of fusion in the scapula + coracoid, carpals, extensor tendon epiphysis, pubis and ischium, etc. However they noticed, “external bone surfaces appear to be fairly well ossified and do not exhibit the coarse, fibrous texture evident in the rostrum and limb bones of embryos.”

Phylogeny
Lü et al. (2012) considered their find an archosaur. They used Euparkeria for an outgroup taxon. While noting similarities to Rhamphorhynchus and considering the specimen immature, oddly Lü et al. (2012) did not test their find against any so-called “immature” Rhamphorhynchus specimens. Their analysis of 37 taxa recovered 550 trees and nested Qinglongopterus with R. muensteri.

That’s 549 Red Flags
IMHO, that’s way too many MPTs for so few taxa.

Testing All the Above
Qinglongopterus was inserted into the matrix of the large pterosaur study, which included eleven Rhamphorhynchus specimens of all sizes. Having so many possible nesting partners covers more contingencies and minimizes problems with taxon exclusion. Here, employing 183 taxa, one MPT (most parsimonious tree) was recovered. That’s complete resolution and inspires high confidence that this tree mirrors nature’s own. Qinglongopterus was recovered as a successor to the BMM Rhamphorhynchus and a predecessor to Wellnhofer’s (1975) No. 10 and No. 11, three Rhamphorhynchus specimens generally and traditionally considered juveniles. But they were not juveniles. They were small adults as demonstrated earlier using phylogenetic analysis. Small specimens are typically found at the bases of all major pterosaur clades as size reduction accompanies major morphological changes in the Pterosauria. Even their feet were distinct (Fig. 2)

Is Qinglongopterus a Rhamphorhynchus?
You decide. If the phylogenetic predecessors of Qinglongopterus were Rhamphorhynchus and its phylogenetic successors were Rhamphorhynchus, what is Qinglongopterus? This is an awkward nomenclature situation akin to the nesting of Nesodactylus within Campylognathoides and Eosipterus within Germanodactylus.

Taxon Exclusion Restricts Nesting Possibilities
Unfortunately Lü et al. (2012) did not test for the possibility that Qinglongopterus might have nested within Rhamphorhynchus by restricting their taxon list to only one Rhamphorhynchus despite a wide gamut of morphological variation within that genus. Adding a few small specimens of Rhamphorhynchus would have tested their ontogenetic and phylogenetic concerns.

Is Qinglongopterus a new Species of Rhamphorhynchus?
Yes. Distinct from sister taxa in the present study manual 2.2 was longer than m2.1. Manual 3.3 was not as long as m3.1 + m3.2. The pes/tibia ratio was relatively smaller than in sisters. Pedal 2.1 was longer than p3.1. The sternal complex was wider than long. Otherwise Qinglongopterus retains certain plesiomorphic traits retained from the BMM specimen and displays certain derived traits not found in the BMM specimen but found in No. 10 and No. 11, like the pointed jaws. The pes of Qinglongopterus is similar to the pes in the BMM specimen (Fig. 2) and the pes of No. 11 .

 

Sample feet of Rhamphorhynchus

Figure 1. Sample feet of Rhamphorhynchus in phylogenetic order. Note the differences in metatarsal and phalanx proportions. These are distinct species, not a growth series of a single species. Figure 2. Rhamphorhynchus pedes demonstrating variation and speciation. The pes of Qinlongopterus is most similar to the BMM specimen and that of No. 11. Click to enlarge.

Is Qinglongopterus Immature?
All sister taxa share the same lack of fusion enjoyed by Qinglongopterus. Earlier we discussed lack of fusion as a phylogenetic trait, not an ontogenetic one. It’s important to remember that pterosaurs do not follow archosaur ontogenetic patterns because they are not archosaurs. Maisano (2002) spelled out the “rules” for lepidosaurs, and pterosaurs follow them.

Fusion Patterns in Pterosaur Ontogeny
Three pterosaur embryos (IVPP specimen, JZMP specimen and Pterodaustro) all have an unfused scapula and coracoid. So do sister taxa (Dimorphodon? weintraubi and Boreopterus) and adults (Pterodaustro). The less developed and largely unossified embryo Darwinopterus had an unfused scapula and coracoid. It’s mother and all sister taxa back to Pterorhynchus fused those elements.

When does fusion take place in taxa with a fused scapulocoracoid?
Maybe at hatching. Maybe later. We don’t know at present.

By the way…
I wrote to Drs. Lü and  Unwin asking why they did not test any purported juvenile Rhamphorynnchus specimens against Qinglongopterus. When  I hear from them, I’ll update this blog.

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
Lü J, Unwin DM, Zhao B, Gao C and Shen C 2012. A new rhamphorhynchid (Pterosauria: Rhamphorhynchidae) from the Middle/Upper Jurassic of Qinglong, Hebei Province, China. Zootaxa 3158:1-19. online first page
Maisano JA 2002. Terminal fusions of skeletal elements as indicators of maturity in squamates. Journal of Vertebrae Paleontology 22: 268–275.

wiki/Qinglongopterus

The Campylognathoides / Rhamphorhynchus Transition

The phylogenetic nestings of Campylognathoides and Rhamphorhynchus are today’s topics.

Unwin 2003
Dr. David Unwin nested Campylognathoides with Eudimorphodon. Rhamphorhynchus nested with Dorygnathus and together these two nested with Scaphognathus and Sordes.

Kellner 2003
Dr. Alexander Kellner also nested Campylognathoides with Eudimorphodon but nested Rhamphorhynchus alone at the base of all pterodactyloid-grade pterosaurs. Dorygnathus, Scaphognathus and Sordes all nested at more basal positions.

Andres et al. 1010
Dr. Brian Andres et al. nested Campylognathoides between Dimorphodon and Scaphognathus (and kin) + Sordes (and pterodactyloids + anurognathids). Rhamphorhynchus nested with Cacibupteryx between several dorygnathids including Dorygnathus and Angustinaripterus.

The Campylognathoidea.

Figure 1. The Campylognathoidea.

The Present Tree
The present large tree, several times larger than any prior tree, and the first and only one to employ more than one specimen from several genera, nested the several species of Rhamphorhynchus following the several species of Campylognathoides and this clade was derived from Eudimorphodon cromptonellus and Eudimorphodon ranzii

No Consensus
It is apparent that no one here agrees with each other, but some share certain elements. Importantly no prior trees nested Rhamphorhynchus with Campylognathoides. This is likely due to the choice of which specimen was used in analysis. The variety within each genus is substantial and certain Rhamphorhynchus specimens do indeed converge with certain Dorygnathus specimens. The large study promoted here used several specimens in order to alleviate this problem. However, what we’re most interested in today is the Campylognathoides to Rhamphorhynchus transition.

the Campylognathoides to Rhamphorhynchus transition

Figure 1. The size reduction at the Campylognathoides to Rhamphorhynchus transition. From left to right: CM 11424, the Pittsburgh specimen of Campylognathoides, St/Ei 8209 Rhamphorhynchus intermedius, and the BMM specimen of Rhamphorhynchus.

Our Transitional Players
The most derived Campylognathoides is the Pittsburgh specimen CM 11424, specimen C3 in the Wild (1975 catalog) from the Early Jurassic. The most basal Rhamphorhynchus is R. intermedius (Koh 1937) , St/Ei 8209, No. 28 in the Wellnhofer 1975 catalog from the Late Jurassic. Not surprisingly, the latter looks like a smaller version of the former and had plenty of time to evolve from it. We know of no Campys in the Late Jurassic and no Rhamphs in the Early Jurassic.

A juvenile?
R. intermedius
was considered a juvenile Rhamphorhychus by Bennett (1995), who used long bone measurements rather than a phylogenetic analysis. R. intermedius was larger than its phylogenetic successors, like R. longicaudus, but smaller than derived Rhamphorhynchus species, like R. longiceps. The phylogenetic size decrease between the specimens was due to serial precocious maturity and serial smaller egg size, as in several other pterosaur lineages.

Differences
Distinct from the C. liasicus, the skull of R. intermedius was relatively larger with a smaller naris and antorbital fenestra. Only one maxillary tooth was enlarged to fang status and like the premaxillary teeth, it was procumbent. The mandible was robust and convex dorsally. Several anterior dentary teeth also leaned anteriorly. The cervicals were slightly longer. The dorsal series was slightly shorter. The scapula and coracoid were not fused. This lack of fusion is not a sign of maturity, but follows phylogenetic lines. The deltopectoral crest was narrower. The ulna + radius was longer. The three distal wing phalanges were shorter and gracile. The  prepubis perforation is expanded beyond the leading edge leaving an anterior process and a ventral process above and below the former perforation. The hind limbs were among the shortest among pterosaurs. The pedal digits were shorter than the metatarsals and digit V was longer than in Campylognathoides.

Size Reduction
In pterosaurs phylogenetic size reduction appears to mimic juvenile characters. But we already know that pterosaur hatchlings were nearly identical to adults. That means the phylogenetic changes precede that hatchling stage and move back into the embryonic stage. Smaller pterosaur adults matured more rapidly than larger pterosaur adults. Smaller pterosaur eggs were ready to hatch sooner than larger pterosaur eggs. These changes produced the smaller wings, tail and legs seen in R. intermedius.

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
Bennett SC 1995. A statistical study of Rhamphorhynchus from the Solnhofen limestone of Germany: year classes of a single large species. Journal of Paleontology 69, 569–580.
Koh TP 1937. Unterscuchungen über die Gattung Ramphorhynchus. – Neues Jahrbuch Mineralogie, Geologie und Palaeontologie, Beilage-Band 77: 455-506.
Padian K 2009. The Early Jurassic Pterosaur Dorygnathus banthenis (Theodori, 1830) and The Early Jurassic Pterosaur Campylognathoides Strand, 1928, Special Papers in Paleontology 80, Blackwell ISBN 9781405192248
Plieninger F 1907. Die Pterosaurier der Juraformation Schwabens. Paläontographica 53: 209-313 & pls 14–19.
Quenstedt FA 1858. Über Pterodactylus liasicus. Jahresheft des Vereins für Vaterlundische Naturkunde in Württemberg 14: 299-310.
Wellnhofer P 1974. Campylognathoides liasicus (Quenstedt), an upper Liassic pterosaur from Holzmaden – the Pittsburgh specimen. Annals of the Carnegie Museum, Pittsburgh, 45: 5-34.
Wellnhofer P 1975a-c. Teil I. Die Rhamphorhynchoidea (Pterosauria) der Oberjura-Plattenkalke Süddeutschlands. Allgemeine Skelettmorphologie. Paleontographica A 148: 1-33.Teil II. Systematische Beschreibung. Paleontographica A 148: 132-186. Teil III. Paläokolgie und Stammesgeschichte. Palaeontographica 149: 1-30.

wiki/Campylognathoides

wiki/Rhamphorhynchus

What’s With That Deep Prepubis?

The “dark wing” specimen of Rhamphorhynchus muensteri JME SOS 4785 (Tischlinger and Frey 2002) has one overlooked oddity worth mentioning. It had an incredibly deep prepubis (Figure 1.)

The darkwing Rhamphorhynchus JME SOS 4785

Figure 1. The darkwing Rhamphorhynchus JME SOS 4785. Note the incredible depth of the prepubis, deeper than in any other pterosaur.

Prepubis
The prepubis of pterosaurs is a pelvic bone not found in the vast majority of tetrapods. It is not homologous with the prepubis of monotremes and marsupials. Nor is it homologous with the so-called “prepubic” bones of crocodilians, which are homologous with the pubic bones of other amniotes (Seeley 1901). The prepubis of ornithischian dinosaurs is a process of the pubis and not a separate ossification.The prepubis is new bone found in all fenestrasaurs (Cosesaurus, Sharovipteryx, Longisquama and pterosaurs).

Radiating from the ventral pubis, the pterosaur prepubis typically has a narrow elongated proximal stem and a thin, plate-like distal expansion. This expansion is often perforated, at times to such an extent that the perforation expands beyond the anterior margin of the prepubis resulting in a forked appearance with anterior and ventral processes. That’s the case in our Rhamphorhynchus. In derived taxa a suture may form at the union (Wellnhofer, 1974). In Pteranodon the prepubes may fuse medially (Bennett, 1991, 2001). The anterior rims of the prepubes contact the posterior rims of the posterior set of gastralia (Bennett 1991, 2000).

Rhamphorhynchus prepubis rotated into the correct position

Figure 2. Prepubis fron Claessens et al. (2009) rotated into the correct position

The Claessens, O’Connor and Unwin (2009) Error
Claessens et al. (2009, Fig. 2) sought to demonstrate the ventral expansion of the pterosaur abdomen to facilitate respiration via “caudoventral rotation of the prepubis.” They described a Rhamphorhynchus prepubis articulated to the pubis with a moveable joint and with its major axis in line with the gastralia. The prepubis was correctly identified, but unfortunately Claessens et al. (2009) failed to notice it had been flipped during taphonomy. The anterior process of the distal prepubis is visible ventral to the pubis. The ventral process is hidden beneath the pelvis. Flipped back and properly configured the prepubis greatly deepens the torso without a moveable joint at the pubis, as in other Rhamphorhynchus specimens, like the “dark wing” example.

So, Why the Deep Prepubis in Rhamphorhynchus muensteri?
Several examples of other Rhamphorhynchus specimens are here, here and here. In certain respects, in none of these does the prepubis reach the depth seen in R. muensteri, somewhat deeper than the pelvis itself and hanging below the knees. The elongated prepubis in R. muensteri ventrally elongates the already wide torso but it doesn’t really create a more voluminous torso because the two prepubes seen in anterior or posterior view form a narrow V shape. I note that in all Campylognathoides (and Nesodactylus) specimens up to but not including the Pittsburgh specimen, the prepubes don’t reach the knees. They don’t even get close. In the Pittsburgh specimen of Campylognathoides, the giant prepubes do extend to the knees. In the tiny basal Rhamphs that follow the prepubes also extend to the knees (in lateral view), but in every case, the femur is relatively short, so the prepubes are not noticeably elongated. That also pertains to the giant, R. longiceps. However, the femur in R. muensteri is relatively longer, and so is the prepubis. Subsequent R. gemmingi specimens either return to the short femur/short(er) prepubis morphology, or the part(s) are missing so comparisons cannot be made so well in the employed specimens. Future reconstructions of more specimens are the next steps in this study.

Other ideas are always welcome.

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
Bennett SC 1991. Morphology of the Late Cretaceous Pterosaur Pteranodon and Systematics of the Pterodactyloidea. [Volumes I and II]. Ph.D. thesis, University of Kansas [Published by University Microfilms International/ProQuest].
Bennett SC 2001. The osteology and functional morphology of the Late Cretaceous pterosaur Pteranodon. Part I. General description of osteology. – Palaeontographica, Abteilung A, 260: 1-112. Part II. Functional morphology. – Palaeontographica, Abteilung A, 260: 113-153.
Claessens, LPAM, O’Connor PM and Unwin DM 2009. Respiratory Evolution Facilitated the Origin of Pterosaur Flight and Aerial Gigantism. PLoS ONE 4(2):e4497. http://www.plosone.org/article/info:doi/10.1371/journal.pone.0004497
Seeley HG 1901. Dragons of the air. An account of extinct flying reptiles. London, Methuen: 1-240.
Tischlinger H and Frey E 2002. Ein Rhamphorhynchus (Pterosauria, Reptilia) mit ungewöhnlicher Flughauterhaltung aus dem Solnhofener Plattenkalk. Archaeopteryx, 20, 1-20.
Wellnhofer P 1974. Campylognathoides liasicus (Quenstedt), an upper Liassic pterosaur from Holzmaden – the Pittsburgh specimen. Annals of the Carnegie Museum, Pittsburgh, 45:5–34.

Rhamphorhynchus. Growth Series? Or Speciation?

One of the biggest mistakes I found in paleontology was the unwarranted lumping of all Rhamphorhynchus specimens under one species based on long bone measurements and statistics. Forsaking phylogenetic analysis, Dr. S. Chris Bennett introduced this hypothesis in 1995 and it has been followed and referenced ever since (Unwin 2005) without confirmation (more below). Phylogenetic analysis was not attempted then (or since).

Figure 1 shows the Rhamphorhynchus clade to scale and in roughly phylogenetic order (left to right) based on the large pterosaur study here. A long list of Rhamphs have never been included in a phylogenetic analysis before, so this is a first. One look (at Figure 1) is all it takes to see the morphological variety present here to say nothing of the phylogenetic size variation. The annotated Nexus file is available on request.

The family tree of the Rhamphorhynchus.

Figure 1. Click to enlarge. The family tree of Rhamphorhynchus to scale. That’s Campylognathoides batting first. The largest of the bunch, no. 81, phylogenetically followed the smallest, No. 10. This clade is ripe for a great dissertation. 

From Large to Small to Giant to Medium-Sized
The genus Rhamphorhynchus is led off by the C3 (Pittsburgh) specimen of Campylognathoides, the phylogenetic ancestor. The basal taxon, R. intermedius (No. 28) was the one closest to Campylognathoides in trait similarity. Continuing the size trend, a smaller series of Rhamphs follow, including R. longicaudus (see below). The giant of the bunch, R. longiceps was followed by a series of medium-sized Rhamphs with longer first wing phalanges and nares set further back on the skull.

One of the Littlest 
Rhamphorhynchus longicaudus (Smith-Woodward 1902, B St 1959 I 400, no. 10 of Wellnhofer 1975, Fig. 2), Late Jurassic ~155 mya, was considered a juvenile by Bennett (1995). Actually it is just another tiny species with a distinct morphology nesting close to other tiny species. Similar in size to and derived from a sister to the BMM specimenno. 10 phylogenetically preceded the giant Rhamphorhynchus longiceps no. 81. Another R. longicaudus specimen, No. 11, actually had proportions more typical of R. longiceps and R. muensteri. It has not been included yet in phylogenetic analysis.

rhamphorhynchus_longicaudus-no10

Figure 2. Rhamphorhynchus longicaudus no. 10. Click for more info.

Distinct from the BMM specimen, the skull of R. longicaudus had a longer, thinner rostrum and a relatively larger skull with a narrower lateral temporal fenestra. No. 10 had a hooked lower jaw longer than its upper, the opposite of most other Rhamphs. It had a low hard crest and a high soft crest on its skull. The anterior teeth were longer and sharper. The cervicals were longer relative to the dorsals. The caudals were more gracile and longer. The sternal complex was somewhat cardiod in shape and reduced in size. The forelimb elements were all more gracile. The posterior is unknown in no. 10, but reconstructed here based on similar specimens. The pubis and ischium were close if not joined. The hind limb elements were all more gracile, including the metatarsals and toes.

Rhamphorhynchus longiceps

Figure 3. Rhamphorhynchus longiceps (Smith-Woodward 1902) BMNH 37002, no. 81 in Wellnhofer 1975. Click for more info.

The Giant of the Bunch
Rhamphorhynchus longiceps (Smith-Woodward 1902, BMNH 37002, no. 81 in Wellnhofer 1975, Fig. 3), was the largest known Rhamphorhynchus. Derived from one of the smallest known species, R. longicaudusR. longiceps phylogenetically preceded R. muensteri.

Distinct from R. longicaudus, the skull of R. longiceps was more robust and longer than the torso. The rostrum was pointed and probably sharpened with a keratinous extension. The orbit was only twenty percent of the skull length. The premaxillary teeth were reduced and bunched together. The anterior dentary was concave dorsally. The cervicals decreased in length anteriorly. Seven sacrals were present. The tail was robust but unknown in length. The dorsal ribs were more robust. The sternal complex was rectangular but gently rounded both anteriorly and posteriorly. The humerus was robust. The posterior ilium was as long as the anterior. The pubis and ischium were separate. The prepubic perforation was filled in. The The pedal digits were longer than the metatarsus.


Growth Series? Or Speciation?
Dr. Peter Wellnhofer (1975) continued the traditional labeling of various Rhamphorhynchus  morphotypes as distinct species. Twenty years later, using statistics measured from long bones, Bennett (1995) envisioned a growth series in Rhamphorhynchus with dramatic morphological changes during maturation. This is a blunder. These specimens are morphologically distinct down to the phalangeal proportions (Peters 2011, Fig. 4) and so represent a phylogenetic sequence. The largest specimen is followed phylogenetically by smaller specimens. We also know from pterosaur embryos that hatchlings greatly resembled their parents and therefore did not go through great morphological changes during maturation. The “juvenilization” during size reduction goes back to accelerated developments at the embryonic stage. Read more about the speciation of Rhamphorhynchus here.

 

Figure 4. Click to enlarge. Rhamphorhynchus pedes.Figure 4. Click to enlarge. Rhamphorhynchus pedes.

Figure 4. Click to enlarge. Note the variety in Rhamphorhynchus pedes. These are not conspecific.

Just Like Pteranodon
A similar phylogenetic blunder without phylogenetic analysis occurred when Bennett (1991, 2001) considered all specimens of Pteranodon restricted to just two species. That hypothesis was challenged here.

An Encouraging Note to Any Future Pterosaur Workers
I hope someone takes this lead and runs with it. A darn good dissertation could be written using two to three dozen Rhamphorhynchus specimens, lumping and separating them.

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
Bennett SC 1995. A statistical study of Rhamphorhynchus from the Solnhofen Limestone of Germany: Year-classes of a single large species. Journal of Paleontology 69: 569–580.
Maisano JA 2002. Terminal fusions of skeletal elements as indicators of maturity in squamates. Journal of Vertebrae Paleontology 22: 268–275.
Peters D 2011. A Catalog of Pterosaur Pedes for Trackmaker Identification. Ichnos 18(2):114-141. http://dx.doi.org/10.1080/10420940.2011.573605
Smith-Woodward A 1902. On two skulls of the Ornithosaurian  Rhamphorhynchus. Annals and Magazine of Natural History, London, (7) 9: 1-5.
Unwin DM 2005. The Pterosaurs: From Deep Time. New York, Pi Press, 1-352.
Wellnhofer P 1975a-c. Teil I. Die Rhamphorhynchoidea (Pterosauria) der Oberjura-Plattenkalke Süddeutschlands. Allgemeine Skelettmorphologie. Paleontographica A 148: 1-33.Teil II. Systematische Beschreibung. Paleontographica A 148: 132-186. Teil III. Paläokolgie und Stammesgeschichte. Palaeontographica 149: 1-30.

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