SVP 21 – a new largely complete istiodactylid pterosaur with a tail!

Rodrigues et al. 2015
describe a new istiodactylid pterosaur (not this one, Fig. 1) with a tail. I have not seen it.

Istiodactylus

Figure 1. This is the Istiodactylus holotype preserved without a tail. I have not seen the pterosaur described in the Rodrigues et al abstract.

From the abstract
“The Istiodactylidae is a clade of Early Cretaceous pterosaurs which possess very distinct teeth, with crowns triangular in shape and strongly compressed labiolingually. A new specimen from this unit is here reported and comprises the most complete istiodactylid found so far. It is an almost complete skeleton of a young animal, with skull, mandible, most of the vertebral column, pectoral and pelvic girdles, most forelimbs and part of the hind limbs. It presents the first information on the tail of the Istiodactylidae and gives a minimum length of 15 caudals. All caudal centra have an elongated cylindrical shape and show no pneumatic foramina. The vertebrae get gradually thinner. The last nine vertebrae show a gradual reduction in length as well. The last caudal is longer than the preceding one but it is the thinnest, with a posterior end a mere 0.3 mm wide. The istiodactylid tail, as expected from pterodactyloids, is short, but it differs from the tail of Pteranodon, which has duplex centra and ends in a caudal rod.”

Actually
that should be paired and parallel caudal rods in Pteranodon and only two specimens preserve a tail. YPM 2462 is represented only by 6 discontinuous caudals and rods. UALVP 24238 (Fig. 2) includes most of the rest of the Pteranodon and the more complete caudals 2-10 of the tail.

Figure 3. The UALVP specimen of Pteranodon. Note the lack of taper in the rostrum along with the small size of the orbit.

Figure 2. The UALVP specimen of Pteranodon. Note the lack of taper in the rostrum along with the small size of the orbit.

Tails in ornithocheirids
The last caudal of the new istiodactylid, at one-third of a millimeter in width, is remarkable in a pterosaur the size of an istiodactylid. By comparison, the more basal ornithocheirid, Zhenyuanopterus (Fig. 3) has a rather extensive tail of at least 40 caudals terminating in a series of extremely thin bones less than a millimeter in length. The tail is longer than the femur + half the tibia.

In Haopterus, an even more basal ornithocheirid, the tail is about as long as its tibia. Boreopterus has a tail almost as long as its hind limb. JZMP embryo has a tail at least as long as its femur. Yixianopterus has a tibia-length tail. The Anhanguera tail is almost a femur in preserved length. Barbosania preserves just a few continuous causals.

Some of these tail lengths
are much longer than expected in ‘pterodactyloid’-grade pterosaurs. Much of that has to deal with the four origins for ‘pterodactyloid’-grade pterosaurs and the traditional biases that expect certain traits under false assumptions of phylogeny that nest short-tailed Pterodactylus close to the origin of all ‘pterodactyloid’-grade pterosaurs.

Zhenyuanopterus

Figure 3. The orinithocheirid Zhenyuanopterus. Note the tail length.

The large pterosaur tree nests Pteranodon (Fig. 2) far from ornithocheirids (Fig. 3). They share few traits other than a warped deltopectoral crest of distinctive designs. Pteranodon is a giant germanodactylid. Ornithocheirids are giant scaphognathids with cycnorhampids as sister taxa. So comparisons to the tail of Pteranodon are illogical in this abstract.

Finally, 
few ornithocheirids fuse their bones. So the new istiodactylid may not be immature, based on prior studies that consider lack of fusion an ontogenetic character. Phylogenetic studies show that pterosaur bone fusion is largely phylogenetic, following patterns established in lepidosaurs (Maisano 2004), not archosaurs.

References
Rodrigues T et al. 2015.
An almost complete istiodactylid (Pterosauria, Pterodactyloiidea) from the Cretaceous of China provides the first information on the tail of this clade.

 

SVP 16 – Cimoliopterus [crested pterosaur], now from Texas!

Myers 2015,
famous for his basal Pteranodon/Germanodactylus, describes a new ornithocheirid with a premaxillary crest in an abstract (see below) and in a JVP paper that just came out.

From the abstract
“Cretaceous strata of Texas have yielded an unexpectedly rich collection of pterosaurs that differ substantially from the prolific, Pteranodon-dominated assemblages of the Western Interior. Two new pterosaur specimens from the Upper Cretaceous Eagle Ford Group in the Dallas/􀂱Fort Worth area enhance our understanding of the fragmentary record of Texas pterosaurs. One specimen (SMU 76892), discovered in the upper Cenomanian portion of the Britton Formation, consists of the rostral section of an upper jaw that bears a prominent, thin premaxillary crest beginning just above the fourth pair of alveoli. The preserved portion of the jaw contains alveoli for 26 teeth, and there is a subtle lateral expansion at the anterior end of the jaw. This partial rostrum is identified as a new species of Cimoliopterus, a monotypic genus previously known only from Cenomanian deposits in England, and represents a significant geographic range extension for this genus. The second new specimen from the Eagle Ford Group (SMU 76942) is a partial upper jaw of Aetodactylus halli, heretofore known only from mandibular material. The jaw fragment was collected at the type locality of A. halli in the middle Cenomanian Tarrant Formation. The dorsoventrally compressed specimen represents part of the anterior half of the jaw, although the exact position within the palate cannot be determined with certainty. The ventral surface bears a thin palatal ridge, and the dorsal surface preserves no evidence of a premaxillary crest. Patterns in tooth spacing along the upper jaw are similar to those observed in the holotype mandible of A. halli (SMU 76383). A phylogenetic analysis of Pterosauria that incorporates the new Cimoliopterus species and new codings for the upper jaw of Aetodactylus indicates that both taxa are basal pteranodontoids. Aetodactylus and Cimoliopterus appear closely related, but are clearly distinct from each other. Identification of Cimoliopterus in North Texas provides further evidence of paleobiogeographic links between the Cretaceous pterosaur faunas of North America and Europe. Discovery of the upper jaw of Aetodactylus confirms that this pterosaur lacked both premaxillary and mandibular crests.”

The Cimoliopterus rostrum
confirms earlier observations of anterior extensions of the nasal and jugal found in other ornithocheirds that extend to the secondary and tertiary nares, both vestigial pores (Fig. 1) recovered by tracing without access to the original specimen.

Destruction
of part of the right side of the rostrum reveals little strips of bone that evidently extended just below the former surface that extend from the nasal and jugal. The fused vomers are the long reported “palatal ridge” described in several ornithocheirids.

Figure 1. Click to enlarge. The rostrum of the North American Cimoliopterus. Every 2 seconds the scenes change. Pink = nasal. Lavender = jugal. Yellow = premaxilla. Green = maxilla. Violet = vomers. DGS enabled the identification of these bones overlooked by first hand observation.

Figure 1. Click to enlarge. The rostrum of the North American Cimoliopterus. Every 2 seconds the scenes change. Pink = nasal. Lavender = jugal. Yellow = premaxilla. Green = maxilla. Violet = vomers. DGS enabled the identification of these bones overlooked by first hand observation.

These extra nares originate also as pores with Scaphognathus (Fig. 2), an ancestral taxon.

Figure 1. Click to enlarge. The reduction of the naris (red arrow), the appearance of the secondary naris, and the appearance of the secondary ascending process of the maxilla in a line of scaphognathids, all to the same scale.

Figure 2. Click to enlarge. The reduction of the naris (red arrow), the appearance of the secondary naris, and the appearance of the secondary ascending process of the maxilla in a line of scaphognathids, all to the same scale. GMu 10157 is basal to the much larger ornithocheirids as recovered in the large pterosaur tree and ignored in the cladograms of other workers.

Note that Myers also traced the nasals and vomers
in Cimoliopterus (Fig. 1) without realizing what they were. That’s where DGS and a good pterosaur cladogram become valuable.

References
Myers TS 2015. New pterosaur material from the Late Cretaceous of North Texas.
Myers TS 2015. First North American occurrence of the toothed pteranodontoid pterosaur Cimoliopterus, Journal of Vertebrate Paleontology, DOI: 10.1080/02724634.2015.1014904

Ikrandraco – the tip of the jaws

This is what you get when you reconstruct a pterosaur with rotating jaws (Fig. 1).

Figure 1. Ikrandraco jaw tips. Here the mandible extends slightly beyond the the rostrum, which has extremely tiny premaxillary teeth.

Figure 1. Ikrandraco jaw tips. Here the mandible extends slightly beyond the the rostrum, which has extremely tiny premaxillary teeth. Yes, that’s a tooth at the mandible tip. Very sharp.

And, going back one post, Ikrandraco does nest between the crested ornithocheirids and the uncreated istiodactylid ornithocheirid. And there’s a set of dorsal ribs beneath the tip of that plant material. That means there’s probably a scapulocoracoid under it, if anyone wants to do a little digging from the back.

 

 

 

Ikrandraco avatar – a new pterosaur & DGS reveals a few more bones

A recent paper
by Wang et al. (2014) described a wonderful new Chinese ornithocheirid, Ikrandraco avatar, with a crest below the mandible, not above the rostrum. Actually two specimens were found with slightly different preservations.

Figure 1. Click to enlarge. Ikrandraco avatar skull. As originally traced (below) with DGS (above).

Figure 1. Click to enlarge. Ikrandraco avatar skull. As originally traced (below) with DGS (above).

This wonderful new ornithocheirid (not a pteranodontoid) from the Jiufotang formation (Early Cretaceous). The authors report, “We propose that this pterosaur fed on fishes from nearby freshwater lakes by flying low over the water, capturing its prey by lowering the mandible in the water, being capable of a reduced and temporary skimming. We also propose that it had a more developed throat pouch then in other pterosaur species.”

The mandible was quite sharp. The rostrum was not. Oddly the teeth appear to have emerged from the sides of the rostrum and mandible. The alveoli were like portholes on a ship’s hull.

Figure 2. Ikrandraco in situ. Below as originally traced. Above with femur, tibia, pelvis and tail traced and manual 4.4 identified (not a rib).

Figure 2. Ikrandraco in situ. Click to enlarge. Below as originally traced. Above with femur, tibia, pelvis and tail traced and manual 4.4 identified (not a rib).

The authors were able to identify the tiny metatarsals and sacrum, but overlooked the tibia, femur, pelvis and tail, shown here (Fig. 2). And yes, that fossil is no closer to me than half a world away. I wouldn’t have looked fro the tibia and femur, but there was the metatarsus, all by itself, lined up with a crack that split the tibia. What I see of the bones are either impressions of bones that were once there, or they remained buried, just below the surface.

Figure 3. DGS restores the known elements to a more in vivo pose of Ikrandraco.

Figure 3. DGS restores the known elements to a more in vivo pose of Ikrandraco. The tiny premaxilla had tiny teeth. Rather than having a nice anhanguerid-like rake and spoonbill, this pterosaurs evolved a very narrow set of jaws. The deep angle of the quadrate absorbed shocks as the lower jaw slid through the water. 

The authors considered this an adult individual based on the fusion of the extensor tendon, but that is a phylogenetic feature shared with several ornithocheirids, large and small.

Other ornithocheirids can be seen here for comparison. Most have longer teeth. Wang et al. (2014) nested Ikrandraco with Nurhachius and Istiodactylus among pterosaurs known from more than just scraps. I haven’t done the work, but that seems reasonable, except that the orbit doesn’t have the keyhole shape. Among pterosaurs with rostral crests and large round orbits, we look to Criorhyrhynchus and Coloborhyrhynchus, which are related to istiodactylids. Unfortunately the authors nested ornithocheirds derived from a sister to sharp-snouted Pteranodon from the Late Cretaceous. That doesn’t make sense. The large pterosaur tree derives ornithocheirids from scaphognathids, sisters to cycnorhamphids and Yixianopterus is a basal ornithocheirid (not included in Wang et al. (2014).

The Ornithocheiridae.

Figure 4. The Ornithocheiridae. Click to enlarge and expand. Look for the taxon that shares the most traits with Ikrandraco. In size Ikrandraco was relatively small, about as tall as Boreopterus. 

 

 

 

References
Wang X, Rodrigues T, Jiang S, Cheng X and Kellner AWA 2014. An Early Cretaceous pterosaur with an unusual mandibular crest from China and a potential novel feeding strategy. Scientific Reports 4 : 6329, pp. 1-9. | DOI: 10.1038/srep06329

The JZMP embryo and its adult sister taxa

Currently the only known embryo/adult pterosaur pairing is in the genus Pterodaustro. Unfortunately, not much has been made about the allometry/isometry in the growth patterns of this genus, even though the data is available. The best data, unfortunately, is right here, rather than in an academic journal. Adults are 8x larger than hatchlings and ontogeny is chiefly isometric (as shown most clearly in Zhejiangopterus) and other pterosaurs like Ptweety the Pteranodon.

For the other two embryos, the IVPP embryo and the JZMP embryo we currently do not have congeneric adults and have to look to sister taxa or simple isometry to estimate the adult proportions and traits.

Today we’ll look at the sister taxa of the JZMP embryo (Fig. 2).

Figure 1. The closest sisters to the JZMP embryo, a basal ornithocheirid without an adult skeleton known for it.

Figure 1. The closest sisters to the JZMP embryo, a basal ornithocheirid without an adult skeleton known for it. Click to enlarge. This is not the phylogenetic order. Yixianopterus is the most primitive. Then the JZMP embryo followed by the smaller forms. These are followed by the boreopterids. 

Generally what we find at clade bases is a gradual increase in size from tiny ancestors. While we do have a tiny ancestor in Pterodactylus(?) pulchellus, we don’t have a gradual increase from that point forward. Yixianopterus the basalmost ornithocheirid, is large AND primitive. The JZMP embryo as an adult, was similar in size to Yixianopterus, but twice as tall as Haopterus and two Lebanon basal ornithocheirids. Click here to see a phylogenetic lineup of ornithocheirids and their outgroup.

Given these various sizes in basal ornithocheirids, and no gradual increase in size, one wonders if Haopterus and the Lebanon ornithocheirids are juveniles. Finding lots of larger congeneric taxa would be helpful. Checking out the annular rings in their long bones would also give clues.

The alternative, that the small ornithocheirids are adults, might represent the next phase in derived ornithocheirid evolution, in which the wings get longer and the feet get smaller, among other traits, which appears to be the case in the Lebanon ornithocheirids.

References
Ji Q, Ji S-A, Cheng Y-N, You HL, Lü J-C, Liu Y-Q and Yuan CX 2004. Pterosaur egg with leathery shell. Nature 432:572.

Moganopterus, boreopterid? or cycnorhamphid?

Moganopterus (Fig. 1, Lü et al. 2012) is one of the oddest of all pterosaurs, with its elongated jaws.

Figure 1. Moganopterus compared to Cycnorhamphus, both to scale.

Figure 1. Moganopterus compared to Cycnorhamphus, both to scale.

Wikipedia follows Lü et al. 2012 in nesting Feilongus (Wang set al. 2005) and Moganopterus with the boreopterid ornithocheirids, Boreopterus and Zhenyuanopterusneither of which have a cranial crest,

Let’s test the nestings
Moving Moganopterus from the cycnorhamphids to the boreopterids adds 17 steps. That’s pretty substantial. Adding Feilongus and Moganopterus to the boreopterids adds 20 steps to the large pterosaur tree.

The resemblances between both clades are remarkable. It is easy how one could waver toward the boreopterids. The Lü et al. 2012 study recovered over 33,000 most parsimonious trees.

Traits shared with cycnorhamphids
Like Cycnorhamphus (Fig. 1) and distinct from boreopterids, Moganopterus has an upper temporal arch set lower on the skull, teeth restricted to the anterior jawline, a cranial crest, a posteriorly descending jugal, and cervical ribs. If anyone has data that could change this nesting, please let me know of it. 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.

Wang X, Kellner AWA, Zhou Z and de Almeida Campos, D 2005. Pterosaur diversity and faunal turnover in Cretaceous terrestrial ecosystems in China. Nature 437 (7060): 875–879. doi:10.1038/nature03982. PMID 16208369.

wiki/Feilongus

 

 

 

3D eggs and a new ornithocheird – Hamipterus

A recent paper
by Wang et al. (2014) introduced us to a new ornithocheirid, Hamipterus (Fig. 1) — AND it’s three-dimensional eggs (Fig. 2). The preservation is atypical: several dozen disarticulated specimens of many sizes were jumbled together, likely following a sudden flood. A Pterodaustro colony was preserved similarly. This sort of preservation can be a blessing and a curse. The parts are buried quickly and we can compare individual and strongly associated elements with those of other pterosaurs, but we cannot create a complete reconstruction except by estimation, especially since so many sizes are represented.

Figure 1. Hamipterus skulls and mandibles compared. Scale bar = 5cm. Ghosted images are from smaller specimens.

Figure 1. Hamipterus skulls and mandibles compared. Scale bar = 5cm. Ghosted images are from smaller specimens. Here skulls are divided according to Wang et al’s assessment of gender based on crest shape. This may be true, and if so represents the first such instance. In other pterosaurs crests are phylogenetic, growing larger or smaller in derived specimens.

Hamipterus — what is it?
Adding Hamipterus to the Wang et al. pterosaur family tree resulted in 324 MPTs with loss of resolution at Hamipterus and elsewhere. Unfortunately they found toothless Pteranodon and Nyctosaurus were the outgroup taxa. Their problem is a result of yet another instance of taxon exclusion.

Let’s correct that by adding taxa.
Adding Hamipterus to the large pterosaur tree resulted in a single MPT. Hamipterus nested between Boreopterus + Zhenyuanopterus and Arthurdactylus + all higher ornithocheirids. Among them only Coloborhynchus has a completely fused pubis and ischium, just like Hamipterus (Fig. 3). None of these were included in the Wang et al. study.

Hamipterus egg.

Figure 2. Hamipterus egg. Scale bar = 1cm. Indented but unbroken like a lepidosaur egg. Evidently no ossified bones were found inside yet.

Eggs
Wang et al. report a total of five eggs were recovered. Most are 59 to 65x34mm in size. One egg was smaller: 30x22mm and considered, “not fully developed.” The shell was pliable, with an ultra-thin calcareous layer followed by a thinner shell membrane, a structure the authors considered similar to that of snakes. (Hmm, and snakes are lepidosaurs!!!). Unfortunately the authors suggest Hamipterus, “likely made its nesting grounds on the shores of freshwater lakes or rivers and buried its eggs in sand along the shore, preventing them from being desiccated.” Of course, another way for them to prevent egg desiccation is to carry eggs within the female until just prior to hatching. Wang et all report that “the eggs are not part of the same clutch and were likely laid by different females, since they were found apart from each other, mixed with bones and subjected to limited transportation.” Of course this would require that buried eggs were excavated before transportation — or they could have been carried within the mother, like many lizards do. Then there’s the half-size egg. That is most likely explained by having a half-sized mom pterosaur. Chinsamy et al. (2008) reported that Pterodaustro reached sexual maturity at half the final adult size. Half-sized moms had half-sized pelves and half-sized eggs.

Ontogeny
Figure S4 in Wang et al. 2014 shows three ulnas with “no significant variation during ontogeny.” Similarly, the small skulls demonstrate no shorter rostra or larger orbits. This confirms the isometric ontogenic patterns shown by Zhejiangopterus, contra the allometric ontogenetic patterns generally accepted by pterosaur workers. It’s just too bad the flood that killed the flock didn’t arrive several weeks later, otherwise we’d see some ossified hatchlings mixed in.

Figure 4. Sternal complex, two pelves and two scapulocoracoids from the Hamipterus beds. These are all good matches for ornithoicheirids near Boreiopterus and Arthurdactylus.

Figure 4. Sternal complex, two pelves and two scapulocoracoids from the Hamipterus beds. These are all good matches for ornithoicheirids near Boreiopterus and Arthurdactylus. Sternal complex shows separate clavicles wrapping around sternum. 

References:
Chinsamy A, Codorniú L and Chiappe LM 2008. Developmental growth patterns of the filter-feeder pterosaur, Pterodaustro guinazui. Biology Letters, 4: 282-285.
Wang X et al.*, 2014. Sexually Dimorphic Tridimensionally Preserved Pterosaurs and Their Eggs from China, Current Biology. http://dx.doi.org/10.1016/j.cub.2014.04.054

*et al includes: Alexander W.A. Kellner, Shunxing Jiang, Qiang Wang, Yingxia Ma, Yahefujiang Paidoula, Xin Cheng, Taissa Rodrigues, Xi Meng, Jialiang Zhang, Ning Li and Zhonghe Zhou

The Humble Origins of the Ornithocheiridae

Earlier we looked at a tiny pterosaur attributed to Pterodactylus” pulchellus at the British Museum of Natural History (NHM  42735) and its ancestry to cycnorhamphids and ornithocheirids. We also looked at the tiny Nohra ornithocheirid from Lebanon. Today we’ll look at these taxa to scale (Fig. 1).

Figure 1. Click to enlarge. The origin of the Ornithocheiridae begins with tiny  "Pterodactylus" pulchellus and continues with the much larger Yixianopterus and the hypothetical adult to the JZMP embryo. Then a size reduction (or is it a juvenile?) to the Nohra Lebanon pterosaur followed by Haopterus, itself about seagull-sized. Thereafter ornithocheirids get larger.

Figure 1. Click to enlarge. The origin of the Ornithocheiridae begins with tiny “Pterodactylus” pulchellus and continues with the much larger Yixianopterus and the hypothetical adult to the JZMP embryo. Then a size reduction (or is it a juvenile?) to the Nohra Lebanon pterosaur followed by Haopterus, itself about seagull-sized. Thereafter ornithocheirids get larger.

From humble beginnings
P. pulchellus (Late Jurassic, Solnhofen) is about as tiny as pterosaurs get. Yet it had already developed traits that put it at the evolutionary crossroads that produced cycnorhamphids in the Solnhofen and yixianopterids (basal ornithocheirids) in the Yixian formation (Early Cretaceous) of China. Other than this specimen, ornithocheirids are curiously absent from the Solnhofen, but by the early Cretaceous they had spread worldwide.

Yet another size reduction – or is it a juvenile?
The Nohra specimen from Lebanon is oddly smaller than its phylogenetic sisters. The only thing holding us back from calling it a juvenile is the relative rarity of juveniles in the fossil record and the presence of small Haopterus ( Fig. 1) as a sister taxon. At this point the Nohra specimen testifies to the unexplored variety in morphology and size that pterosaurs present us.

You can see more ornithocheirids to scale here.

Cearadactylus and the importance of adding taxa to family trees

A recent paper by Vila Nova et al. (2014) on the ornithocheirid pterosaur Cearadactylus atrox (Fig. 1) corrects earlier errors and posits a phylogenetic position for it. 

Figure 1. Cearadactylus atrox.

Figure 1. Cearadactylus atrox correctly reconstructed, as Vila Nova et al. 2014 reconstruct it.

Originally the premaxilla was reconstructed as the dentary tip and vice-versa. The Vila Nova paper corrects this by flipping those rostral elements back the way they should be.

The problem with Vila Nova et al. is a reliance on traditional family trees
that include Pteranodon (Fig. 2) as sister taxa to ornithocheirids. This is based on the purported shared trait of a warped deltopectoral crest, and that’s about it. And the design of those warps share nothing in common. The rest of their bodies  share traits that are common to many or most pterosaurs. Think about it. Anhanguera (Fig. 2) a close relative of Cearadactylus) is a giant Scaphognathus. Pteranodon is a giant Germanodactylus.

Figure 2. Cearadactylus, Anhanguera and Pteranodon compared. The inset compares the humerus of Anhanguera and Pteranodon.

Figure 2. Cearadactylus, Anhanguera and Pteranodon compared. The inset compares the humerus of Anhanguera and Pteranodon. Think about it. Anhanguera is a giant Scaphognathus. Pteranodon is a giant Germanodactylus.

Who would match these two??
After all, Pteranodon has a long sharp toothless beak, nothing like what you see in Cearadactylus (Fig. 2). Here (Fig. 3) are the trees that Vila Nova et al. employed.

Figure 2. Cearadactylus family trees employed by Vila Nova et al. 2014. Inclusion of Pteranodon and Nyctosaurus is incorrect when more taxa are added (Fig. 4).

Figure 3. Cearadactylus family trees employed by Vila Nova et al. 2014. Inclusion of Pteranodon and Nyctosaurus is incorrect when more taxa are added (Fig. 3).

Missing from the Vila Nova tree are all the basal ornithocheirids, like Haopterus, Arthurdactylus and the rest shown here (Fig. 4). Also missing, if you’re going to include Pteranodon and and Nyctosaurus are all the basal Germanodactylus and tiny pterosaurs arising from Scaphognathus, including the last common ancestor of Pteranodon and Cearadactylus: the tiny pterosaur specimen TM13104.

Figure 3. The pterosaur subset of the large reptile tree showing the nesting sites of Cearadactylus (yellow) and Pteranodon and Nyctosaurus (black arrows) so far apart.

Figure 3. The pterosaur subset of the large reptile tree showing the nesting sites of Cearadactylus (yellow) and Pteranodon and Nyctosaurus (black arrows) so far apart.

Adding taxa, especially tiny taxa, is key to the understanding of pterosaur interrelationships. Traditional trees are good starts, but they must be expanded.

Otherwise you get strange bedfellows that nest together without sharing very many traits.

References
Dalla Vecchia FM 1993. Cearadactylus? ligabuei, nov. sp., a new Early Cretaceous (Aptian) pterosaur from Chapada do Araripe (Northeastern Brazil)”, Bolletini della Societa Paleontologica Italiano, 32: 401-409.
Leonardi G and Borgomanero G 1985. Cearadactylus atrox nov. gen., nov. sp.: novo Pterosauria (Pterodactyloidea) da Chapada do Araripe, Ceara, Brasil. Resumos dos communicaçoes VIII Congresso bras. de Paleontologia e Stratigrafia, 27: 75–80.
Unwin DM 2002. On the systematic relationships of Cearadactylus atrox, an enigmatic Early Cretaceous pterosaur from the Santana Formation of Brazil. Mitteilungen Museum für Naturkunde Berlin, Geowissenschaftlichen Reihe 5: 1239–263.
Vila Nova BC, Kellner AWA, Sayão JM 2010. Short Note on the Phylogenetic Position of Cearadactylus Atrox, and Comments Regarding Its Relationships to Other Pterosaurs. Acta Geoscientica Sinica 31 Supp.1: 73-75.
Vila Nova BC, Sayão JM , Neumann VHML and Kellner AWA 2014. Redescription of Cearadactylus atrox (Pterosauria, Pterodactyloidea) from the Early Cretaceous Romualdo Formation (Santana Group) of the Araripe Basin, Brazil, Journal of Vertebrate Paleontology, 34:1, 126-134.

wiki/Cearadactylus

Derived Ornithocheirids – Where are the prepubes??

All pterosaurs have a prepubis, right?
That’s that little addition to the pubis that only fenestrasaurs, including pterosaurs, have, convergent with marsupial bones in mammals. Oddly they are not often found in several ornithocheirids, which are not often found articulated.

Zhenyuanopterus is complete and articulated, but the prepubes, if present, would be beneath the crushed pelvis.

Where found, as in the basal ornithocheirids,m JZMP embryo, Boreopterus, Haopterus, Arthurdactylus and the large istiodactylid, SMNK PAL 1136, the prepubes are typically small with a slender stem and a broader ventral plate. We still haven’t found prepubes for  Anhanguera, Tropeognathus, Coloborhynchus, Brasileodactylus, Nurhachius or Istiodactylus (Fig. 1). Still looking.

The Ornithocheiridae.

Figure 1. The Ornithocheiridae. Click to enlarge and expand.