The larger specimen of Sinopterus atavismus enters the LPT basal to dsungaripterids

Many pterosaur fossils attributed to Sinopterus
have been described. They vary greatly in size and shape.

Presently four Sinopterus specimens have been added
to the large pterosaur tree (LPT, 253 taxa). They are all sister taxa, but as in Archaeopteryx, no two are alike, one is basal to the others, which are, in turn, basal to large clades within the Tapejaridae.

  1. Sinopterus dongi (the holotype) nests basal to the Tupuxuara clade.
  2. Sinopterus liui nests in the Tupuxuara clade.
  3. Sinopterus jii (aka Huaxiapterus jii) nests basal to the Tapejara clade.
  4. Sinopterus atavisms (Figs. 1-4; Zhang et al. 2019; IVPP V 23388) nests basal to the Dsungaripterus (Fig. 4) clade, outside the Tapejaridae.

Figure 1. Sinopterus atavismus in situ.

Figure 1. Sinopterus atavismus in situ. IVPP V 23388

From the Zhang et al. 2019 abstract:
“Here, we report on a new juvenile specimen of Sinopterus atavismus from the Jiufotang Formation of western Liaoning, China, and revise the diagnosis of this species.”

Zhang et al. note that several elements are unfused including a humeral epiphysis. Several pits and grooves in the distal ends of the long bones are also pitted and grooved. Normally these would be good indicators in archosaurs and mammals, but pterosaurs are lepidosaurs and lepidosaurs follow distinctly different ‘rules’ for growth (Maisano 2002). As an example, some pterosaur embryos have fused elements. Some giant pterosaurs have unfused elements. Here the new specimen (IVPP 23388) is considered an ontogenetic adult as its size is similar to other phylogenetic relatives.

“Sinopterus atavismus does not present a square-like crest. Moreover the feature that groove in the ventral part of the second or third phalanx of manual digit IV is not diagnostic of the species.”

Zhang et al. are comparing the new larger IVPP specimen to the smaller, previously described (Lü et al. 2016) XHPM 1009 specimen (then named Huaxiapterus atavismus), which they considered conspecific. The XHPM specimen has wing phalanx grooves while the IVPP specimen does not. The shapes of the skulls do not match (Fig. 3) and we know that pterosaurs grew isometrically. Thus these two specimens are not conspecific.

“In the new material, the skull preserves a pointed process in the middle part of the dorsal marginof the premaxillary crest, which is different from other Chinese tapejarids. Considering the new specimen is known from a large skeleton that differed from the holotype, this difference may be related to ontogeny, as the premaxillary crest of the holotype is short and does not extend as long as that of the new specimen.”

These two specimens are not conspecific, so ontogenetic comparisons should not be made.

Figure 2. Sinopterus atavismus reconstruction.

Figure 2. Sinopterus atavismus reconstruction.

From the Zhang et al. 2019 discussion:
“Except for D 2525 which represents an adult individual of Sinopterus (Lü et al. 2006b), all Chinese tapejarid pterosaurs known so far were immature individuals at the time of death. The new specimen (IVPP 23388) shares some features with the holotype of Sinopterus atavismus. The wingspan of the new material is about twice as long as that of the holotype of S. atavismus.”

As mentioned above, the IVPP V 23388 specimen is here considered an adult with unfused bone elements. It needs both a new generic and specific name. The XHPM 1009 specimen (Fig. 3) requires further study.

Figure 3. Sinopterus atavismus size comparison

Figure 3. Sinopterus atavismus size and shape comparison.

The present confusion about the ontogenetic status of pterosaurs 
could have been largely resolved with the publication of “The first juvenile Rhamphorhynchus recovered by phylogenetic analysis” and other papers suppressed by pterosaur referees. Sorry, readers, we’ll have to forge ahead with the venues we have.

Figure 3. Sinopterus atavismus skull restored (gray areas).

Figure 4. Sinopterus atavismus skull restored (gray areas).

Figure 4. Sinopterus atavisms compared to Dsungaripterus to scale.

Figure 5. Sinopterus atavisms compared to Dsungaripterus to scale.

Sinopterus atavismus (Zhang et al. 2019; Early Cretaceous; IVPP V 23388) was originally considered a juvenile member of the Tapejaridae, but here nests as a small adult basal to Dsungaripteridae. The antorbital fenestra is not taller than the orbit. The carpals are not fused. No notarium is present. The antebrachium is robust. The distant pedal phalanges are longer than the proximal pedal phalanges. An internal egg appears to be present (but half-final-size adults were sexually mature according to Chinsamy et al. 2008,)

Sinopterus dongi IVPP V13363 (Wang and Zhou 2003) wingspan 1.2 m, 17 cm skull length, was linked to Tapejara upon its discovery, but is closer to Tupuxuara.

Sinopterus? liui (Meng 2015; IVPP 14188) is represented by a virtually complete and articulated specimen attributed to Sinopterus, but nests here at the base of Tupuxuara longicristatus.

Sinopterus jii (originally Huaxiapterus jii, Lü and Yuan 2005; GMN-03-11-001; Early Cretaceous) is basal to the Tapejara in the LPT, distinct from the other sinopterids basal to Tupuxuara.

Figure 5. Click to enlarge. The Tapejaridae arise from dsungaripterids and germanodactylids.

Figure 5. Click to enlarge. The Tapejaridae arise from dsungaripterids and germanodactylids.

The present LPT hypothesis of interrelationships
appears to be a novel due to taxon inclusion, reconstruction and phylogenetic analysis. If not novel, please let me know so I can promote the prior citation.

Traditional phylogenies falsely link azhdarchids with tapejarids
in an invalid clade ‘Azhdarchoidea‘. The LPT has never supported this clade (also see Peters 2007), which is based on one character: an antorbital fenestra taller than the orbit (that a few sinopterids lack). Pterosaur workers have been “Pulling a Larry Martin” by counting on this one character and by excluding pertinent taxa that would have shown them this is a convergent trait ever since the first cladograms appeared in Kellner 2003 and Unwin 2003.

Figure 1. Gene studies link swifts to hummingbirds. Trait studies link swifts to owlets. Trait studies link hummingbirds to stilts.

Figure x. Gene studies link swifts to hummingbirds. Trait studies link swifts to owlets. Trait studies link hummingbirds to stilts.

Unrelated update:
The stilt, Himantopus (Fig. x) has moved one node over and now nests closer to the hummingbird, Archilochus. Both arise from the Eocene bird, Eocypselus, which also gives rise to the hovering seagull, Chroicocephalus. The long, mud probing beak of the stilt was adapted to probing flowers in the hummingbird. All these taxa nested close together in the LRT earlier.


References
Chinsamy A, Codorniú L and Chiappe LM 2008. Developmental growth patterns of the filter-feeder pterosaur, Pterodaustro guinazui. Biology Letters, 4: 282-285.
Kellner AWA 2003. 
Pterosaur phylogeny and comments on the evolutionary history of the group. Geological Society Special Publications 217: 105-137.
Lü J and Yuan C 2005. 
New tapejarid pterosaur from Western Liaoning, China. Acta Geologica Sinica. 79 (4): 453–458.
Maisano JA 2002. The potential utility of postnatal skeletal developmental patterns in squamate phylogenetics. Journal of Vertebrate Paleontology 22:82A.
Maisano JA 2002.
Terminal fusions of skeletal elements as indicators of maturity in squamates. Journal of Vertebrae Paleontology 22: 268–275.
Peters D 2007. The origin and radiation of the Pterosauria. In D. Hone ed. Flugsaurier. The Wellnhofer pterosaur meeting, 2007, Munich, Germany. p. 27.
Unwin DM 2003. On the phylogeny and evolutionary history of pterosaurs. Pp. 139-190. in Buffetaut, E. & Mazin, J.-M., (eds.) (2003). Evolution and Palaeobiology of Pterosaurs. Geological Society of London, Special Publications 217, London, 1-347.
Wang X and Zhou Z 2003. A new pterosaur (Pterodactyloidea, Tapejaridae) from the Early Cretaceous Jiufotang Formation of western Liaoning, China and its implications for biostratigraphy. Chinese Science Bulletin 48:16-23.
Zhang X, Jiang S, Cheng X and Wang X 2019. New material of Sinopterus (Pterosauria, Tapejaridae) from the Early Cretaceous Jehol Biota of China. Anais da Academia Brasileira de Ciencias 91(2):e20180756. DOI 10.1590/0001-3765201920180756.

wiki/Sinopterus

The Aathal specimen enters the LPT at the base of the Tapejaridae

Updated November 18, 2020
with the realization that this is not Sinopterus jii, as previously noted. I believed an online image that labeled it such and did not reference earlier comments. Apologies for the confusion.

Earlier I found this image of a sinopterid with broken wings
as I sought the specimen number in order to nest it in the large pterosaur tree (LPT, 253+ taxa). A kind reader (TG) replied it was from the Sauriermuseusm in Aathal, Germany.  Today it enters the LPT.

Figure 1. Sinopterus jii in situ. Note the broken arms.

Figure 1. Sinopterus jii in situ. Note the broken arms.

Reconstructions of the body and skull
enabled scoring of the Aathal specimen as it nested basal to tapejarids. Two Sinopterus specimens nested basal to the tupuxuarids. Outgroups include other China pterosaurs in the Dsungaripteridae and Shenzoupteridae.

Figure 1. The Sauriermuseum Aathal specimen. Scale remains unknown.

Figure 1. The Sauriermuseum Aathal specimen. Scale remains unknown.

Figure 3. Sauriermuseum Aathal skull in situ and reconstructed.

Figure 3. Sauriermuseum Aathal skull in situ and reconstructed.

The frontal + parietal crest on the Aathal specimen
is distinctive and points to a wider variation than typically imagined for this genus.

Phylogenetic Note
The antorbital fenestra is not taller than the orbit in the Aathal specimen (Fig. 3). Traditional phylogenies link azhdarchids with tapejarids in an invalid clade ‘Azhdarchoidea‘. The LPT has never supported this clade (also see Peters 2007), which is based on one character: an antorbital fenestra taller than the orbit. Pterosaur workers have been “Pulling a Larry Martin” by counting on this one character and by excluding pertinent taxa that would have shown them this is a convergent trait ever since the first cladograms appeared in Kellner 2003 and Unwin 2003.

Figure 4. Click to enlarge. The Tapejaridae arise from dsungaripterids and germanodactylids.

Figure 4. Click to enlarge. The Tapejaridae arise from dsungaripterids and germanodactylids.

Small pterosaurs are usually small adult pterosaurs, 
not juveniles, contra traditional thinking. There are a few notable exceptions herehere and here.


References
Kellner AWA 2003. Pterosaur phylogeny and comments on the evolutionary history of the group. Geological Society Special Publications 217: 105-137.
Lü J and Yuan C 2005. 
New tapejarid pterosaur from Western Liaoning, China. Acta Geologica Sinica. 79 (4): 453–458.
Peters D 2007. The origin and radiation of the Pterosauria. In D. Hone ed. Flugsaurier. The Wellnhofer pterosaur meeting, 2007, Munich, Germany. p. 27.
Unwin DM 2003. On the phylogeny and evolutionary history of pterosaurs. Pp. 139-190. in Buffetaut, E. & Mazin, J.-M., (eds.) (2003). Evolution and Palaeobiology of Pterosaurs. Geological Society of London, Special Publications 217, London, 1-347.

wiki/Sinopterus

Darwin’s finches: Mesozoic style

Originally ‘Darwin’s finches’ =
small birds from the Galápagos Islands west of Ecuador, in the Pacific Ocean.

According to Wikipedia:
The term “Darwin’s finches” was first applied by Percy Lowe in 1936, and popularised in 1947 by David Lack in his book Darwin’s Finches. The most important differences between species are in the size and shape of their beaks, which are highly adapted to different food sources.”

For today’s post, metaphorically speaking, ‘Darwin’s finches’ =
“several variations on a last common ancestor restricted to a small geographic area.”

Similar Mesozoic variations
on a last common ancestor restricted to a small geographic area are also documented in the large reptile tree (LRT) and the large pterosaur tree (LPT). Here (Figs. 1–8), other than Late Cretaceous Pteranodon (Fig. 1), and Middle Jurassic Darwinopterus (Fig. 8), the others (Figs. 2–7), are all known from the Late Jurassic Solnhofen Formation, a lagerstätte representing an archipelago or series of islands, much like today’s Galápagos Islands.

Here
(Figs. 1–8) pictures of closely related taxa tell the story of their own evolution much better than any long-winded explanation. No two are alike. Arrows indicate phylogenetic order.

If you want to know more,
click on each of the images below. When taken to the large image pages at ReptileEvolution.com a small link at the top of each page will take you to one of the species pictured therein. Other links to related taxa are posted on each species’ page.

Pteranodon

Figure 2. The DMNH specimen is in color, nesting between the short crest KS specimen and the long crest AMNH specimen.

Figure 1. The DMNH specimen is in color, nesting between the short crest KS specimen and the long crest AMNH specimen. If you see a female in this diagram, let me know. No two are alike.

Rhamphorhynchus

Figure 2. Rhamphorhynchus specimens to scale. The Lauer Collection specimen would precede the Limhoff specimen on the second row.

Figure 2. Rhamphorhynchus specimens to scale. The Lauer Collection specimen would precede the Limhoff specimen on the second row. No two are alike, but the Vienna specimen is a juvenile of the larger n81 specimen to its right.

Dorygnathus

Figure 8. Click to enlarge. The descendants of Sordes in the Dorygnathus clade and their two clades of pterodactyloid-grade descendants.

Figure 3. Click to enlarge. The descendants of Sordes in the Dorygnathus clade and their two clades of pterodactyloid-grade descendants. No two are alike.

Germanodactylus

Germanodactylus and kin

Figure 4. Click to enlarge. Germanodactylus and kin. No two are alike.

Pterodactylus

The Pterodactylus lineage and mislabeled specimens formerly attributed to this "wastebasket" genus

Figure 5. Click to enlarge. The Pterodactylus lineage (in white) and mislabeled specimens formerly attributed to this “wastebasket” genus (in color boxes). No two are alike.

Scaphognathus

Figure 1. Scaphognathians to scale. Click to enlarge.

Figure 6. Click to enlarge. Only the left three taxa have been identified as Scaphognathus species. Other tiny unnamed specimens are transitional taxa to Pterodactylus or Germanodactylus leading to larger, later taxa. No two are alike.

Archaeopteryx (some of these Solnhofen birds have been renamed)

Figure 3. Several Solnhofen birds, including Archaeopteryx, compared to Ostromia to scale.

Figure 7. Several Solnhofen birds, including Archaeopteryx, compared to Ostromia to scale. No two are alike.

Darwinopterus

Figure 7. Darwinopterus specimens and a few outgroup taxa.

Figure 8. Darwinopterus specimens and a few outgroup taxa. None of these are basal to any pterodactyloid-grade clades. No two are alike. The female (upper right) is associates with an egg.

Unfortunately,
PhDs and other paleo workers who traditionally refuse to trace and reconstruct ‘to scale’ skeletons of taxa under study never get to discover results like these that are only revealed from producing ‘to scale’ graphics like these (Figs. 1–8). Subtleties come through here, en masse, that are lost when looking at individual skeletons in situ one at a time, especially through a microscope, where you don’t get to see ‘the big picture’. Some workers consider such graphics pseudoscience and crankery.

As a result, no other workers
understand or accept the four origins of the pterodactyloid grade arising from phylogenetic miniaturized transitional taxa (Figs. 3, 6) because they omit pertinent tiny and congeneric taxa. Likewise, workers do not yet understand nor accept the radiation of several bird clades having their genesis in Solnhofen basalmost birds. Workers don’t see ‘the big picture’ because of these taxon exclusions.

Rather, too many workers
try to compile a list of specific traits that differentiate one taxon from another. Here we call that, “Pulling a Larry Martin” because it only sometimes leads to greater understanding. The problem is unrelated taxa too often share those same traits by convergence. Here, reconstructions and a confident nesting in the LRT automatically encompass and include ALL the subtle irregularities between taxa that ‘trait seekers’ traditionally overlook.

References

wiki/Darwin’s_finches

SVP abstracts – the Skye pterosaur

Martin-Silverstone, Unwin and Barrett  2019 bring us
news of a new Middle Jurrasic Scottish pterosaur: the Skye pterosaur.

From the abstract
“The Middle Jurassic was a critical time in pterosaur evolution – a series of major morphological innovations underpinned radiations by, successively, rhamphorhynchids, basal monofenestratans, and pterodactyloids. Frustratingly, however, this interval is also one of the most sparsely sampled parts of the pterosaur fossil record, consisting almost exclusively of isolated fragmentary remains.”

…other than all the many complete Jianchangnathus, Changchengopeterus, Pterorhynchus, Darwinopterus, and Dorygnathus specimens, that is. Why are these three pterosaur experts pretending these wonderfully preserved taxa don’t exist?

Figure 1. Skye pterosaur from traced from in situ specimens found online.

Figure 1. Skye pterosaur in ventral view traced from in situ specimen photos found online with limbs duplicated graphically. This preliminary data was enough to nest it in the LPT better than three PhDs with a set of µCT scans hampered by their much smaller unresolved pterosaur cladogram.

Martin-Silverstone et al. continue:
“Here we report on the most complete individual found to date, a three-dimensionally
 preserved, partial pterosaur skeleton recovered in 2006 from the Bathonian-aged Kilmaluag Formation, near Elgol, Isle of Skye, Scotland. Micro-CT scanning, segmentation, and 3D-reconstruction using Avizo has revealed multiple elements of the axial column, fore-, and hind limbs, many of which were fully embedded within the matrix and inaccessible via traditional preparation and imaging techniques.”

“Unique features of the coracoid distinguish the Skye pterosaur from all other species, indicating that it represents a new taxon.”
“The new specimen was included in phylogenetic analysis that was conducted using maximum parsimony in PAUP on a data matrix consisting of 61 taxa scored for 136 morphological characters. This analysis generated 544,320 MPTs.
OMG!!! What a confession!! That is a sign of a  lousy cladogram!!
“The 50% majority rule tree places the Skye taxon as a basal monofenestratan in a clade with Darwinopterus, Wukongopterus, and, for the first time, Allkaruen, which was previously identified as non-monofenestratan.
The LPT confirms the nesting of the Skye pterosaur with Darwinopterus, but closer to Jianchangnathus and Pterorhynchus (Fig. 2). In the LPT, Alkaruen nested basal to the ctenochasmatid, Pterodaustro. Details on that here.

Figure 3. Subset of the LPT showing the nesting of the Skye pterosaur from available data (Fig. 1).

Figure 2. Subset of the LPT showing the nesting of the Skye pterosaur from available data (Fig. 1). This is a terminal clade with no known descendants, contra Martin-Silverstone, Unwin and Barrett.

The Skye pterosaur, one of the earliest, most complete records for Monofenestrata, provides critical new insights into pterosaur evolution.”
The large pterosaur tree (LPT, 241 taxa; subset Fig. 2) once again finds no evidence for a monophyletic Monofenestrata and the entire LPT is resolved. If the Martin-Silverstone, Unwin and Barrett team added 180 taxa they would also find no evidence for a monophyletic Monofenestrata and their resolution would increase.
“The distal end of the Skye pterosaur’s scapula is expanded and articulated with the vertebral column, a feature shared with other basal mononfenestratans. Comparisons across Pterosauria show that this type of bracing was far more widespread than previously realized and seemingly present in many clades, with the exception of basal-most (Late Triassic) forms. The development of a notarium, providing additional stability and support, is confined to derived and often large and giant species and forms only part of the complex evolutionary history of the scapulo-vertebral contact.”
They could have simply said, a notarium is present. Instead they took a paragraph to do so, omitting many other traits that could have been mentioned. When scientific data is published, the authors of that data open their work for criticism and assistance. In that way errors are corrected and omissions are included.
Googling ‘Skye pterosaur’ results in several hits
including this classified ad from a year ago seeking a paleo student to work with a set of pterosaur expert PhDs. Hope it was a fulfilling experience for that student.
“Closing in January 2019: We seek a student with experience in studying and describing fossil and/or living animal specimens, comparative vertebrate anatomy, a broad background in biological and/or geological sciences, and experience or a willingness to learn statistical and CT techniques. As the student will be working with a large team, teamwork skills and a collaborative mindset are essential.” palass.org/careers

References
Martin-Silverstone E, Unwin DM and Barrett PM  2019. A new, three-dimensionally preserved monofenestratan pterosaur form the Middle Jurassic of Scotland and the complex evolutionary history of the scapulo-vertebrael articulation. Journal of Vertebrate Paleontology abstracts.

Geographic cladogram of pterosaurs

So many pterosaurs come from so few places.
And those places are spread around the world. So, here (Fig. 1) is the large pterosaur tree (LPT, 239 taxa) with color boxes surrounding Solnhofen, Chinese, North American, South American and other geographic areas where they are found.

Figure 1. LPT with pterosaurs colorized according to geography.

Figure 1. LPT with pterosaurs colorized according to geography.

As before,
the traditional clades ‘Pterodactyloidea’ and ‘Monofenestrata‘ become polyphyletic when traditionally omitted taxa are included. Here (Fig. 1) four clades achieve the pterodactyloid-grade by convergence. Other pterosaur workers (all PhDs) omit or refuse to include most of these taxa, leading to false positives for the tree topologies they recover. Moreover, none recognize, nor cite literature for, the validated outgroup members for the Pterosauria (Fig. 1) preferring to imagine pterosaurs arising from unidentified and/or invalidated archosaurs or archosauriforms. Here we get to peak beneath the curtain.


References
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 2007. The origin and radiation of the Pterosauria. In D. Hone ed. Flugsaurier. The Wellnhofer pterosaur meeting, 2007, Munich, Germany. p. 27.

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.

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.

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

SVP 11 Pterosaur pelvic morphology

Frigot 2015 
provides general information about pterosaur pelves using principal component analysis, similar to that of Bennett 1995, 1996. I hope it works out better for Ms. Frigot.

From the abstract
“Pterosaurs have modified the basic triradiate amniote pelvis, extending the ilium into elongate processes both anterior and posterior to the acetabulum. While pterosaurs are now generally accepted to move quadrupedally on the ground*, many hypotheses exist regarding the diversity of gaits and terrains exploited across Pterosauria and how this may be correlated with the shifts in body plan found at the base of the monofenestratans and of the pterodactyloids. Early attempts to bring comparative anatomy to bear upon the topic have been largely descriptive of pelvic shape across the clade. I attempt to rectify this by providing a geometric morphometric analysis of a phylogenetically diverse sample of pterosaur pelves. Using landmark-based methods, shape was captured at the bone margins and acetabulum, with a view to capturing surfaces available for muscle attachment. These landmarks were analyzed using principal components analysis (PCA). Principal components 1 and 2 distinguish well between genera, reducing possible concerns over the role of taphonomy and ontogeny in determining shape**. It is not apparent whether the lack of a phylogenetic trend across shape space is due to small sample size or a high degree of evolutionary plasticity, highlighting the need for a greater sample size. However, with this support for a biological signal in the data, subsequent steps can be made that focus on biomechanical and locomotor analyses using detailed anatomical observations. We can then try to identify how pelvic disparity might have led to a diversity of locomotor styles in this most unique taxon.”***

*That’s traditional thinking. Many pterosaur tracks indicate bipedal locomotion.
**Ontogeny does not change pelvis shape because pterosaurs grew isometrically.
***So, sorry… no taxa or conclusions here.

References
Frigot RA 2015. The pterosaurian pelvis. An anatomical view of morphological disparity and implications for for locomotor evolution.

Trees of Life: Birds and Pterosaurs

Yale’s Richard Prum recently announced that the Tree of Life of Birds is almost complete. A genomic analysis of 198 species of birds was published in the Oct. 7 edition of the journal Nature. Prum reported, ““In the next five or 10 years, we will have finished the tree of life for birds.” I presume that means fossil taxa will also be included and scored by morphological traits because genes (genomic traits) are not available.

It is not the first time…
Trees of Life for Birds were announced earlier here, here, here and here.

Having been through a similar study, I support all such efforts. AND I will never attempt to add any but a few sample birds to the large reptile tree. Others have better access to specimens and they have a big head start on the process.

Unfortunately,
some workers have ignored the pterosaur tree of life. Recently Mark Witton ignored isometric growth patterns in pterosaurs to agree with Bennett (2013) that the genus Pterodactylus includes tiny short-snouted forms, mid-sized long-snouted forms (including the holotype, of course) and large small-heron-like forms. Witton reports, “Speaking of adulthood, it was also only recently that we’ve obtained a true sense of how large Pterodactylus may have grown. We typically imagine this animal as small bodied – maybe with a 50 cm wingspan – but a newly described skull and lower jaw makes the first unambiguous case for Pterodactylus reaching at least 1 m across the wings (Bennett 2013).”

We looked at Bennett’s paper earlier in a three part series that ended here. The taxon Witton refers to is actually just a wee bit larger than the holotype and is known from a skull, so wingspread can only be guessed. The tiny short-snouted forms are actually derived from the short-snouted scaphognathids as shown here.

The Pterodactylus lineage and mislabeled specimens formerly attributed to this "wastebasket" genus

Figure 1. Click to enlarge. The Pterodactylus lineage and mislabeled specimens formerly attributed to this “wastebasket” genus. Others have split the largest specimens of Pterodactylus from the others without employing a phylogenetic analysis.

You might recall
that one of the largest complete Pterodactylus specimens (Fig. 1) recovered by the large pterosaur tree was mistakenly removed from this genus and lumped with Ardeadactylus, a basal pre-azhdarchid, all without phylogenetic analysis.

Agreeing with Bennett,
Witton deletes some taxa that actually belong to this genus, while accepting others that do not belong, all based on eyeballing specimens without a phylogenetic analysis that includes a large gamut of specimens (that does not delete the tiny forms). Eyeballing taxa is not the way to handle lumping and splitting. Phylogenetic analysis is. We looked at the Pterodactylus wastebasket problem here.

References
Bennett  SC 2012 [2013]. New information on body size and cranial display structures of Pterodactylus antiquus, with a revision of the genus. Paläontologische Zeitschrift (advance online publication) doi: 10.1007/s12542-012-0159-8
http://link.springer.com/article/10.1007/s12542-012-0159-8

News on the Origin of Pterosaurs on YouTube

I just uploaded a pterosaur origins video on YouTube. Click here to view it.

Click to view this "Origin of Pterosaurs" video on YouTube.

Click to view this “Origin of Pterosaurs” video on YouTube. 17 minutes long. 

Back to Cuspicephalus: Germanodactylid? or Wukongopterid?

Earlier we looked at the gracile skull of Cuspicephalus which nested with Germanodactylus B St 1892 IV 1 in the large pterosaur tree.

Today we revisit this taxon after the publication of Witton et al. 2015, which attempted to related Cuspicephalus to Darwinopterus and the wukongopterids.

Cuspicephalus scarfi

Figure 1. Cuspicephalus scarfi. Click to enlarge. Note the round exoccipital process at the back of the skull. Germanodcatylids have these. Wukongopterids do not. Witton thinks that bone is an artifact.

I have rarely seen a paper with such a bogus foundation…

  1. Witton et al. support the ‘modular’ evolution of pterosaurs at the base of the Pterodactyloidea. Earlier we learned that with the simple addition of taxa (which other workers continue to avoid) there are four origins for pterodactyloid-grade pterosaurs, all following phylogenetic miniaturization, a process that happens often in reptile evolution. We also learned that there is no such thing as ‘modular’ evolution with half the body evolving and waiting for the other half to catch up. In the case of wukongopterids, the other half never developed pterodactyloid-grade traits. Wukongopterids were a terminal taxon. The non-modular evolution of long tails to short tails happened several other times at several other nodes in the pterosaur cladogram (including in the anurognathids).
  2. With several distinct genera and specimens now nesting close to Darwinopterus robustus within the Wukongopteridae, no attempt was made to figure out which of these specimens were more basal and which were more derived — as shown in the large pterosaur tree.
  3. Witton et al. support a monophyletic “Monosfenestrata” which, to them, includes pterodactyloids + wukongopterids, a tree topology that is not supported by any other published studies. In the large pterosaur tree, wukongopterids, like anurognathids, convergently developed some pterodactyloid-grade traits and not others, then left no descendants.
  4. Witton et al. did not produce their own skull tracings, but rely on cartoonish and inaccurate versions of prior work by others (apparently often by Bennett 1996). Few to no skull sutures are shown and certain inaccuracies are present.
  5. Witton et al. are not critical of the cladistic work of others (Andres et al., 2014; (Lü et al., 2010; Tischlinger and Frey, 2014), nor do they offer support for the matrix they preferred (Unwin 2003). Seems less scientific than one would like to see here. Or did they not want to do the work? Or make enemies?

Figure 2. Cuspicephalus compared to Darwingopterus and to Germanodactylus, all to scale.

Figure 2. Cuspicephalus compared to Darwingopterus and to Germanodactylus, all to scale. Click to enlarge. The large reptile tree nests Cuspicephalus with Germanodactylus. Witton et al. report a closer relationship to Darwinopterus. The presence of large exoccipital ‘ears’, an extended cranium, a pointed rostrum, a pointed ventral orbt, an alignment of the rostral crest and antorbital fenestra anterior margin all argue for the present hypothesis. The longer antoribital fenestra developed by convergence in Darwinopterus and Cuspicephalus.

Granted,
wukongopterid skulls are indeed very similar to those of germanodactylids (Fig. 2). Both clades also offer a wide variety of shapes and sizes.

With regard to a key trait
in Cuspicephalus scarfi (MJML K1918) from Witton et al. 2015: The exoccipital processes are unexpanded: they look relatively large on MJML K1918, but this is largely an artefact of distortion around the occipital region, and they are not as prominent as those of Germanodactylus or dsungaripterids.

Actually
in Cuspicephalus the exoccipitals are just as big, if not bigger relative to skull height (Fig. 2).

In the large pterosaur tree
Cuspicephalaus nests with B St 1892 IV 1, n61 in the Wellnhofer (1970) catalog, which nests with two headless taxa, Wenupteryx (MOZ 3625) and the so-called “Crato azhdarchide (SMNK PAL 3830)”

From Witton et al. “Our assessment suggests that wukongopterid skulls can be distinguished from other Jurassic monofenestratans by not only lacking the well-documented cranial  synapomorphies of pterodactyloid clades, but also through a unique combination of characters (Darwinopterus, Gemanodactylus and Cuspicephalus = D, G and C):

  1. Striated bony crest lower than the underlying prenarial rostrum, with sloping anterior margin – actually lower in G.
  2. Anterior crest terminates in the posterior region of the prenarial rostrum, closer to the anterior border of the nasoantorbital fenestra than the jaw tip – note the crest starts more anteriorly in D
  3. Reclined, but not sub-horizontal, occipital regions leans more in G.
  4. Piriform (pear-shaped) orbitbut in G and C the orbit is sharply angled ventrally
  5. Convex anterodorsal orbital marginmore convex in G + C.
  6. Short nasal processonly in D.
  7. Unexpanded exoccipital processesonly in D.
  8. Concave dorsal skull surfacenot on G, D or C.
  9. Straight ventral skull surfacepresent on G, D and C.
  10. Nasoantorbital fenestra over 50% of jaw length – on D and C
  11. Small, equally sized alveoli – only on C, larger teeth on D and G.
  12. First alveolus pair located on anterior face of jaw, with mandible over-bitten by first premaxillary tooth pair – present on G, D and C
  13. Regular tooth spacing – only on D
  14. Interalveolar spacing generally greater than tooth length – only on D
  15. Dentition extends under anterior half of the nasoantorbital region – only on G and C
  16. Relatively slender, sharply pointed conical teeth – only on C.

Chronology
Cuspicephalus is Kimmeridgian (Late Jurassic) in age. So is Germanodactylus (Kimmeridigian/Tithonian). Darwinopterus is late Middle Jurassic (Bathonian/Oxfordian) in age. No wukongopterids are found in Late Jurassic deposits. So far…

I can see why there is confusion here. 
The skulls are very similar in overall morphology. But the weight of evidence appears to lend weight to a Germanodactylus relationship for Cuspicephalus. If Witton et al. had made more precise tracings and reconstructions, if they had used a valid tree topology that included tiny pterosaurs, if they had not discounted the presence of exoccipital processes on Cuspicephalus, then I think they would have come up with a nesting that echoed that of the large pterosaur tree.

An outlandish suggestion based on a cladogram
We have a large germanodactylid skull without a body (Cuspicephalus) and we have a large germanodactylid post-crania without a skull (the Crato Azhdarchide). Although they are separated somewhat in time, they are sister taxa. Wonder how well the real skull and real post-crania would match up with these two…

Diopecephalus = P. longicollum = Ardeadactylus. Normannognathus is in the box in the lower left.

Figure 3. Witton et al. also attempted to resolve the relationships of Normannognathus without success. Here it is in the box at lower left. Phylogenetic analysis nests it with Diopecephalus = P. longicollum = Ardeadactylus.

Normannognathus
Witton et al. also considered the problem of the placement of Normannognathus (Fig. 3). Earlier we looked at the phylogenetic relationships of Normannognathus (Buffetaut et al. 1998;  MGC L 59’583) known from a toothy, curved rostrum and crest. While Witton et al. considered the problem too difficult to solve, several years ago Normannognathus was matched to the big Pterodactylus longicollum (SMNS-56603, No. 58 of Wellnhofer 1970), which was not considered by Witton et al.

References
Andres B, Clark J, Xu X. 2014. The earliest pterodactyloid and the origin of the group. Current Biology 24: 1011-1016.
Bennett SC 1996. Year-classes of pterosaurs from the Solnhofen limestones of Germany: taxonomic and systematic implications. Journal of Vertebrate Paleontology 16:432–444.
Lü JC, Unwin DM, Jin X, Liu Y, Ji Q. 2010. Evidence for modular evolution in a long-tailed pterosaur with a pterodactyloid skull. Proceedings of the Royal Society B 277: 383-389.
Tischlinger H and Frey E 2014. Ein neuer Pterosaurier mit Mosaikmerkmalen basaler und pterodactyoider Pterosaurier aus dem  Ober-Kimmeridgium von Painen (Oberpfalz, Deutschland) [A new pterosaur with moasic characters of basal and pterodactyloid Pterosauria from the Upper Kimmeridgian of Painten (Upper Palatinate, Germany)]. Archaeopteryx 31: 1-13.
Witton MP, O’Sullivan M and Martill DM 2015. The relationships of Cuspicephalus scarfi Martill and Etches, 2013 and Normannognathus wellnhoferi Buffetaut et al., 1998 to other monofenestratan pterosaurs.