Tapejara Juvenile??

The post cranial skeleton of Tapejara (famous for its head crests) was published last year (Eck, Elgin and Frey 2011). It was smaller than the known skulls (Fig. 1). I had seen the 3D skeleton in a museum drawer several years ago. The skull despite its size, is very close in morphology to the holotype. The smaller specimen may bea juvenile and if so it demonstrates, once again, the largely isometric, rather than allometric growth pattern of pterosaurs, although in this case the rostrum is shorter and the eyeball greater. These clues might indicate that the specimen could be a smaller species on that basis alone, given the examples of embryos and other juveniles that do not share “juvenile” traits with adults. Too bad the feet are unknown in both cases. They usually tell the tale. A Tapejara foot was looked at earlier, but it was from another specimen.

Various Tapejara specimens including the juvenile.

Figure 1. Various Tapejara specimens including the purported juvenile. Click to learn more. The postcrania of the large Tapejara was based on the smaller specimen and the toes were from a disarticulated specimen.

Eck K, Elgin RA, Frey E 2011. On the osteology of Tapejara wellnhoferi KELLNER 1989 and the first occurrence of a multiple specimen assemblage from the Santana Formation, Araripe Basin, NE-Brazil. Swiss Journal of Palaeontology, doi:10.1007/s13358-011-0024-5.

Cope’s Rule and Pterosaurs

In one of his first papers on pterosaurs, Dr. David Hone teamed with mentor Dr. Mike Benton in 2006 to report, “…the pterosaurs, show increasing body size over 100 million years of the Late Jurassic and Cretaceous, and this seems to be a rare example of a driven trend to large size (Cope’s Rule).” They used a best fit regression line drawn perfectly straight to demonstrate size increase through time. While their results were true, that straight line and their caption (Fig. 1) missed all the real excitement of the journey itself.  Unfortunately they reported, “Wingspans measured from juveniles…were excluded.” 

So they missed all the tiny adult pterosaurs at the bases of several major clades.

 Copes Rule in Pterosaurs as plotted by Hone and Benton 2007

Figure 1. Copes Rule in Pterosaurs as plotted by Hone and Benton 2007. Color cloud added. Despite the overall rise from tiny basal pterosaurs to Quetzalcoatlus, note the several dips over time despite the complete exclusion of tiny transitional pterosaurs in several clades. If pterosaurs had died out any time before 130mya, the regression line would have been even to slightly down.

Straight: Not Great.
Not sure why a straight line was so important. It’s presence negated all possibility of seeing any sort of rise and fall of size on the graph over time — which, after all, was the whole point! The various rises and falls are colored above (Fig. 1). While it is certainly true that early pterosaurs were smaller than the largest pterosaurs of all time, basically the Hone/Benton (2006) strategy negated all possibility of any other result based on the details, a pattern these two followed later (Hone and Benton 2007/2008) in trying to negate the possibility of fenestrasaurs as pterosaurs by eliminating them.

Forget the Graph, What Does Their Data Tell Us?
Let’s skip the straight line for now and keep our eye on the data alone. Just looking at the dot/plots on the graph, some pterosaurs from 225 mya were larger than any others for 75 million years. Then there’s a sharp decrease at 132 mya followed by a large rise. Then another dip at 100 mya ending with Quetzalcoatlus at the end of the Cretaceous. With such a specimen at the end, and no small to medium pterosaurs in the Late Cretaceous, any sort of straight line had to extend up over time.

If We Plotted Dinosaurs, What Would the Graph Look Like?
Dinosaurs, like mammals and reptiles, started small and got big. So their regression line would also rise. Among dinosaurs, sauropods would have plotted highest, but they are all extinct now and none of the really big ones were present in the Late Cretaceous. The average of all modern birds (ostrich to hummingbird) would probably fall somewhere between sparrows and storks (I’m guessing). So, if the data began with tiny Marasuchus, the best-fit regression line might tilt up slightly over time. If so, that would “prove” Cope’s Rule within bird evolution. Whether the line rose or fell slightly from the Triassic to the Present is interesting and quaint, but not the point. The point is: once again we’d miss all the rises and falls (at the K-T boundary) within the lineage over time. It’s the journey, not the destination.

What If Those Purported Juveniles Were Adults?
Readers of The Pterosaur Heresies certainly know the answer to this one. It’s a constant theme. The base of every major pterosaur clade began with a series of ever smaller then gradually larger specimens, unmatchable to any known adults.  Beyond the dips in the graph noted earlier, the insertion of the tiniest of pterosaur adults would have deepened several of the dips, or created their own dips. It’s also clear from the graph that no effort was made to follow specific clades of pterosaurs. For instance, Hone and Benton (2006) had no idea that Quetzalcoatlus arose from tiny ancestors like No. 42 and No. 44, which were themselves tiny descendants of much larger Dorygnathus specimens.

Good for What it is, But Missed The Point
Cope’s Rule did operate within the Pterosauria, as it did in every other tetrapod clade, but in smaller doses separated by intervals of size reduction. These should not have been overlooked or ignored.

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.

Hone and Benton 2006. Cope’s Rule in the Pterosauria, and differing perceptions of Cope’s Rule at different taxonomic levels. Journal of Evolutionary Biology 20(3): 1164–1170. doi: 10.1111/j.1420-9101.2006.01284.x
Lawson DA 1975. Pterosaur from the latest Cretaceous of West Texas: discovery of the largest flying creature. Science 187: 947-948.


Ornithocheirid or Tapejarid?

Sometimes all that is discovered of a Santana pterosaur specimen is a big elongated wing. From past experience we know that two clades filled prehistoric Santana skies, members of the Ornithocheiridae close to Anhanguera, and members of the Tapejaridae close to Tupuxuara and Tapejara. Now Vila Nova and Sayão (2012) have cleared things up. Their new paper plots wing dimensions for both clades, recovering two separate clouds of data. That means wings without skulls can now be identified by dropping their data into the graph and seeing which cloud it nests in.

The two clouds of data. Above, the Anhangueridae. Below the Tapejaridae.

Figure 1. The two clouds of data. Above, the Anhangueridae. Below the Tapejaridae.

The Vila Vova and Sayao (2012) report highlights an important aspect to evolution. There is no modular evolution as discussed earlier. When a taxon evolves it does so from head to tail, sometimes unevenly, but this report on distinct wing finger proportions is directly in line with earlier reports of distinct free finger and feet proportions (Peters 2011).

Good science.

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.

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
Vila Nova BC and Sayão JM 2012. 
On wing disparity and morphological variation of the Santana Group pterosaurs, Historical Biology: An International Journal of Paleobiology.


Binocular Vision in Pterosaurs

Binocular vision in certain birds is well known (Fig. 1). You can read more about it online here. Most birds have eyes on the sides of their heads. Apparently most have some degree of binocular vision. However, owls are different, with eyes rotated to the front for the skull. This occurs largely by the increased width of the back of the skull. The beak was always narrow, so narrowing of the beak was never an issue. Eagles and hawks have more binocular vision than most birds, other than owls.

Binocular bird vision.

Figure 1. An old image, perhaps from the 50-year-old Time/Life series, illustrating bird vision in a sparrow, a woodcock and an owl. The overlapping dark orange areas represent binocular vision. Most birds are like the sparrow, but many have some degree of binocular vision. 

Binocular vision in pterosaurs is a largely untouched subject. Most pterosaurs did not have much binocular vision. With eyes on the sides of its head, Pteranodon (Fig. 2) is such an example. It could view its entire world, but had to tilt its head one way or the other to see straight ahead. Many birds are similar.

The skull of Pteranodon in dorsal view without the possibility of binocular vision.

Figure 2. The skull of Pteranodon in dorsal view without the possibility of binocular vision.

Anurognathid Pterosaurs
Basal anurognathids, like Dendrorhynchoides (Fig. 3) also had eyes on the sides of their head, but note the slightly greater width at the back of the skull. Anurognathids evolved from a sister to Dimorphodon, Preondactylus and several other dimorphodontoids, including the IVPP embryo, all with small eyes at the back of their skull and little to no binocular vision. Perhaps binocular vision has been ignored by pterosaur workers largely because no others have bothered to accurately reconstruct the skulls of the only pterosaurs with substantial binocular vision, the owl-like anurognathids.

Dorsal and lateral views of three anurognathid pterosaurs.

Figure 3. Dorsal and lateral views of three anurognathid pterosaurs. From left to right, Dendrorhynchoides, Batrachognathus and Jeholopterus, all crushed dorsoventrally, due to the skull’s greater width.

The frontals were expanded laterally behind the very large eyeballs of Batrachognathus. The large upper temporal openings were likely filled with large muscles, larger than those of other anurognathids. The rostrum was shorter than in Dendrorhynchoides. Of all the known pterosaurs, Batrachognathus was the most owl-like. The scerlotic ring filled the orbit, which probably restricted the movements of the eye within the orbit. The skull had to be rotated to change the view. The large eyes also may indicate a nocturnal lifestyle.

The other derived anurognathid is Jeholopterus, the vampire pterosaur (Fig. 3). It had smaller eyes and a smaller pair of frontals, but they were angled like those of Batrachognathus. Considering the large size of the orbit and the small size of the eyeball itself (as revealed by the small sclerotic ring) one can imagine that such an eyeball had a greater ability to rotate within the skull, looking both sideways and somewhat forwards. Once latched onto its prey, there was no longer any need to look forwards, only to watch out for fellow vampires coming in from above to feast alongside it.

The other Jeholopterus(?)
The CAGS specimen had little to no binocular vision despite its closer relations with the above two anurognathids.  A relatively broad set of nasals and relatively small upper temporal fenestra provided excellent vision to each side, but not much up front.

As always, I encourage readers to see specimens, make observations and come to your own conclusions. Test. Test. And test again. Pterosaur workers, don’t be afraid to attempt your own reconstructions of anurognathid skulls. The bones are all there. I’ve provided guides to several specimens, but make your own observations. Don’t blindly follow the autapomorphic monstrosity of Bennett (2007). Test it with your own tracings and share your results.

Evidence and support in the form of nexus, pdf and jpeg files will be sent to all who request additional data.

There are no published studies of binocular vision in pterosaurs. If you know of some, let me know.

Pterosaur Tree Clingers and Non-Clingers

While we know of bipedal and quadrupedal pterosaur tracks left in soft mud and sand, we will never have traces of pterosaurs clinging to trees. Nevertheless, certain pterosaurs have provided clues that they did so, or could have done so, while others could not.

Four pterosaur hands with fingers of various sizes.

Figure 1. From left to right the pterosaurs MPUM 6009, Dorygnathus, Pterodaustro and Nyctosaurus, all to the same relative metacarpus length demonstrating the relative size of the free fingers. Those with larger free fingers were more adapted to cling to trees.

Tree Clinging in Pterosaurs
Tree clinging goes back to LongisquamaCosesaurus and perhaps even Huehuecuetzpalli and Lacertulus, basal tritosaur lizards that had tendril-like hind toes, like a modern Iguana. Unlike Iguana, Huehuecuetzpalli and Lacertulus had relatively smaller hands, fingers and finger claws. A quick look at the modern glider, Draco, can be instructive on this point. Giant claws may not be necessary, but long tendril-like fingers seem to help.

The pterosaur ancestor Longisquama had relatively enormous fingers tipped with trenchant claws and a bipedal body plan. So it clung to trees in a different fashion than a typical lizard — and more like a telephone lineman (or a lemur) with feet planted beneath the hips, the belly elevated off the trunk, the arms extended and the fingers wrapped around the trunk, claws dug in. Finger 4 was rotated axially and posteriorly at the carpus. Despite its great length, finger 4 was no longer involved with tree clinging, as demonstrated by the discontinuous PILs (described here).

Like their Lizard Forebearers
Early pterosaurs, like MPUM 6009 (Fig. 1) and Dorygnathus (Fig. 1) had relatively long fingers tipped with trenchant, bark-stabbing claws.  Primitively their metacarpals and fingers increased in length from 1 to 4. In Dorygnathus metacarpal 2 and 3 were subequal.

Derived Pterosaur Hands
In certain later pterosaurs the metacarpals would appear in different proportions.  Pterodaustro (Fig. 1) had relatively tiny fingers on metacarpals in which mc 1 was longer than mc2, which was longer than mc3. Digit 2 was subequal to 3 and no manual ungual was deeper than its penultimate phalanx.

A series of Nyctosaurus specimens demonstrate the reduction of all three fingers in that genus, culminating in the UNSM93000 specimen which had useless wire-like vestiges.

Needlessly Controversial
In the present supposedly “heretical” configuration the forearm was unable to pronate or supinate, thus the palmar side of the fingers faced ventrally in flight and medially with wings folded (Peters 2002). This controversy was blogged about earlier. The key here is the palmar sides of the fingers facing medially with wings folded so pterosaurs could grapple parasagittal tree trunks between their opposing hands, much like the early bird, Archaeopteryx, which had similarly elongated fingers and a forearm similarly unable to pronate and supinate. Other scientists proposed finger configurations that were permanently supinated (i.e. Bennett 2008), but these did not allow tree clinging.

Azhdarchids, even large ones, had robust fingers with deep claws. Were they found in trees? Or only on the ground?

Jeholopterus had extremely long, curved hand claws, built like surgeon’s needles. These look to be ideal for stabbing and clinging to dinosaur hide. Were these clues to its vampire lifestyle?

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.

Bennett SC 2008. Morphological evolution of the forelimb of pterosaurs: myology and function. Pp. 127–141 in E Buffetaut and DWE Hone eds., Flugsaurier: pterosaur papers in honour of Peter Wellnhofer. Zitteliana, B28.
Peters D 2002. A New Model for the Evolution of the Pterosaur Wing – with a twist. – Historical Biology 15: 277–301.

The Completeness of the New Reptile and Pterosaur Family Trees

The news that the Chinese pterosaur, Guidracowas most closely related to the South American Ludodactylus points to the worldwide distribution of the Ornithocheiridae, a clade of long-ranging pterosaurs. Probably not such a surprise for such wide-ranging albatross-like flyers. We also have North and South American anurognathids, Chinese Rhamphorhynchus, African dsungaripterids and South American ctenochasmatids, to name a few. We’re not coming up with anything outlandish anymore.

A Complete Pterosaur Tree
The Guidraco news points to the virtual completeness of the pterosaur family tree. Despite its unusual and exaggerated traits, Guidraco nested well within established clades. No presently known pterosaur is an outlier taxon. All are nested. I haven’t found an oddball in the bunch. Other than the terminal taxa (those that left no descendants), all pterosaurs fit somewhere between two others.

And Complete Reptile Tree
The same is true of dinosaurs and reptiles in general. Every taxon finds a sister. All enigmas are nested. The family trees are complete or virtually so.

Reason to Celebrate? Depends on Your Attitude.
One of the drivers of science is the search for answers and the revelation of mysteries. So what happens when virtually all of those mysteries are already solved? Does that take all the fun out? Have we already seen the Golden Age of enthusiasm and insight? Like a jigsaw puzzle that is almost done and missing just a few pieces, the present family trees indicate that future discoveries are likely to be more or less predictable ~ with new discoveries nesting between something we already are familiar with.

Works With Less Than Complete Specimens too.
The present trees are filled with skull only and skull-less taxa, as well as a few others of lesser quality. Even so, the data provides enough resolution to resolve long-standing mysteries and upset traditional paradigms (enabled by lack of testing better candidates).

The New Trees Work Like Clockwork, But That Doesn’t Take All the Fun Out.  Predictability is generally agreed to be a good trait in science, as in the Periodic Table of Elements. The new large tree provides that sort of predictability and complete resolution. The only frustration now is general adoption (hopefully by testing!!).

While others struggle with their own (let’s face it: botched) pterosaur and reptile trees, fraught with resolution problems and sisters that don’t look similar, I encourage workers to add more and more taxa to replicate the full resolution recovered in the trees presented in reptileevolution.com, because…

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.

Patterns in the Reduction of Pedal Digit 5 in Pterosaurs

Updated April 5, 2016 with a new image of Nemicolopterus.

That Very Weird Pedal Digit 5
Basal pterosaurs had an elongate pedal digit 5, emanating from a short metatarsal 5 and composed of two hyperflexed metatarsal-length phalanges tipped by an often overlooked ungual for a total of three phalanges.  Peters (2000) reported that pedal digit 5 impressed the hyperflexed dorsal surface of pedal 5.2/3 (= fused phalanges) into the matrix, as demonstrated by Rotodactylus tracks. Peters (2000) attributed matched Rotodactylus to a pterosaur outgroup sister, Cosesaurus. Peters (2011) attributed similar tracks with pedal digit 5 impressing far behind the other four digitigrade impressions to anurognathids and a specific Rhamphorhynchus.

Basal Tritosaur, Fenestrasaur and Pterosaur feet with digit 5 bones color coded.

Figure 1. Click to enlarge. Basal tritosaur, fenestrasaur and pterosaur feet with digit 5 bones color coded. Note the fusion of pedal 5.2 and 5.3 in pterosaurs. Find any single archosaur or set of archosaurs with a similar pedal digit 5 and you’ll have found the archosaur sister to pterosaurs. Good luck! Question for you: does the brevity of p5.3 in Cosesaurus and Longisquama mean it ultimately disappeared? Or did it fuse with p5.2? I think the latter, but the data is not quite there yet. 

Where Did It Come From?
Pterosaurs inherited that elongated toe 5 from their fenestrasaur and tritosaur ancestors, all of which (e.g. Tanystropheus) had an extra phalanx (Fig. 1). Pedal 5.2 fused to p5.3 in the most primitive known pterosaurs, so the ungual is p5.4, as in the basal lizards, Lacertulus and Huehuecuetzpalli (Fig. 1). In basal pterosaurs and Sharovipteryx, pedal 5.1 often extended to or beyond the distal end of metatarsal 4, but it does not do so in more primitive taxa. In several derived clades pedal digit 5 became reduced, sometimes to a vestige. We’ll look at those patterns of reduction today.

Distinct from Lacertulus, metatarsal 5 was shorter and pedal digit 5 was longer in Huehuecuetzpalli (Fig. 1). This set up the classic pattern seen in the most members of the Tritosauria (langobardisaurs, drepanosaurs, tanystropheids and fenestrasaurs). Exceptions and reductions follow.

Note: absolutely no archosaurs or archosauriformes have an elongated pedal digit 5. This trait alone should have been enough to steer workers away from the conventional and traditional “pterosaurs are archosaurs” hypothesis.

Macrocnemus. Note the reduction of pedal digit 5.

Figure 2. Macrocnemus. Note the reduction of pedal digit 5. The resemblance of this skull to that of Campylognathoides (Fig. 3) is both somewhat homologous and by convergence. Several transitional taxa differ more. 

The first instance of pedal digit 5 reduction occurred in Macrocnemus. The entire digit was shorter than metatarsal 4 and the phalanges of digit 5 were shorter distally.  A derived macrocnemid, Dinocephalosaurus, likewise had a small pedal digit 5, but it extended as far at the base of p4.2 as this reptile developed paddle-like, swimming feet. Find the missing Macrocnemus without this toe reduction and you’ll have the transitional taxon linking this genus closer to tanystropheids, langobardisaurs, drepanosaurs and fenestrasaurs.

Campylognathoides (CM 11424), the earliest pterosaur with a reduced pedal digit 5.

Figure 3. Campylognathoides, the earliest pterosaur genus with a reduced pedal digit 5. All known specimens had a reduced pedal digit 5. 

The first pterosaur with a stunted pedal digit 5 was Campylognathoides (Fig. 3)All known specimens had a stunted pedal digit 5 in which pedal 5.1 extended no further than half the length of metatarsal 4. Not sure why this is so. The current predecessor taxon, Eudimorphodon cromptonellus, did not have a reduced pedal digit 5, but overall E. cromptonellus was much smaller. Perhaps pedal digit 5 is the one body part that did not enlarge, phylogenetically, as the rest of the body grew larger.

A taxon derived from a sister to the most derived CampylognathoidesCM 11424, Rhamphorhynchus intermedius (St/Ei 8209, No. 28 in the Wellnhofer 1975 catalog), had a longer pedal digit 5 that extended at least 3/4 of the length of metatarsal 4. So the reduction was reversed to become an elongation in Rhamphorhynchus. Pedal digit 5 varied in length in other Rhamphorhynchus specimens, with some extending no further than half the length of metatarsal 4 and others extending to the full length of metatarsal 4.

Two sister taxa bridging the basal/derived pterosaur divide.

Figure 4. Two sister taxa bridging the basal/derived pterosaur divide. TM 10341 was much smaller than the SMNS 50164 specimen of Dorygnathus (enlarged to the right). Despite the short metacarpal and long pedal digit 5, the tiny dorygnathid was considered a Pterodactylus by Wellnhofer, who listed it as No. 1 in his 1970 catalog. Pedal digit 5 no smaller relative to metatarsal 4 in the tiny sister. 

Tiny Dorygnathids Leading Toward Azhdarchids
Typical Dorygnathus specimens, like SMNS 50164, had a very large pedal digit 5, with p5.2 bent, even so, in this taxon pedal 5.1 did not extend beyond metatarsal 4, but aligned with the line extending along mt3 and mt4. Despite the large size reduction in TM 10341 (No. 1 in the Wellnhofer 1970 catalog), pedal 5.1 extended just as far. In the larger taxon, Beipiaopterus, pedal 5.1 did not extend beyond half of metatarsal 4. It was similar in No. 44 and No. 42. Pedal 5.1 did not become smaller than half of metatarsal 4 until the base of the Azhdarchidae, represented by Jidapterus. Peters (2000a, 2011) found a correlation between the reduction of pedal digit 5 and plantigrady in these taxa.

The MB.R. 3530.1 specimen

Figure 5. The MB.R. 3530.1 specimen wrongly attributed to Pterodactylus (No. 40 in the Wellnhofer 1970 catalog).

Tiny Dorygnathids Leading Toward Ctenochasmatids
Similar in fashion to the above scenario, MB.R.3530.1 (No. 40 in the Wellnhofer 1970 catalog, Fig. 5) was smaller overall and had a shorter pedal digit 5 and it became progressively shorter in more derived ctenochasmatids like Ctenochasma. In these taxa pedal digit 5 is not typically found hyperflexed, but extends its full (even though abbreviated) length alongside metatarsal 4.

No Reduction in Cycnorhamphids + Ornithocheirds
Relative to metatarsal 4, pedal digit 5 does not become reduced in the monophyletic clade of cycnorhamphids + ornithocheirids. However, because metatarsal 4 becomes so short in derived ornithocheirids like Anhanguera, pedal digit 5 likewise becomes small — but not relatively small.

Pedal digit 5 in a basal Pterodactylus, AMNH 1945.

Figure 6. Pedal digit 5 in a basal Pterodactylus, AMNH 1945.

In all specimens for Pterodactylus pedal 5.1 extends no further than half of metatarsal 4 (Fig. 6).

The smallest pterosaur. No. 6

Figure 7. The smallest of all adult pterosaurs, B St 1967 I 276 or No. 6 in the Wellnhofer (1970) catalog. At left is the foot plantigrade and with metatarsals slightly raised, which simplifies and aligns the PILs (parallel interphalangeal lines). The gray oval is a hypothetical egg based on the pelvic opening. The sternal complex is also shown separated from the lateral view reconstruction.

No. 6
The smallest of all known adult pterosaurs, B St 1967 I 276 (No. 6 in the Wellnhofer 1970 catalog, Fig. 7) extended pedal 5.1 no longer than 2/3 the length of metatarsal 4 but in larger taxa, like No. 12 and No. 23, pedal 5.1 extends to a point in line with metatarsals 3 and 4, still shorter than metatarsal 4. This pattern is also found in several other Germanodactylus specimens.

Figure 8. A larger view of Nemicolopterus. Pedal digit 5 is relatively reduced here.

Figure 8. A larger view of Nemicolopterus. Pedal digit 5 is relatively reduced here.

Nemicolopterus to Tupuxuara
The tiny pterosaur Nemicolopterus (IVPP-V-14377, Fig. 8) had a pedal 5.1 no longer than half the length of metatarsal 4. The larger sister, Shenzhoupterus, had a longer metatarsus and a shorter pedal digit 5. This pattern continues in Huaxiapterus with a reduction to a nub in Tupuxuara.

Right pes, dorsal view of Pteranodon UALVP 24238. Note pedal digit 5 is a vestige.

Figure 9. Right pes, dorsal view of Pteranodon UALVP 24238. Note pedal digit 5 is a vestige on this plantigrade foot.

No. 13 to Pteranodon
Despite the large number of Nyctosaurus and Pteranodon specimens, few preserve toe bones (Fig. 9).  Fewer still preserve digit 5 toe bones. No digit 5 toe bones are known in Nyctosaurus. A basal Pteranodon FHSM VP 2183 preserves pedal 5.1 extending no further than 1/3 the length of metatarsal 4, which is rather elongate. In derived Pteranodon specimens pedal digit 5 becomes much shorter, but the foot remains digitigrade. In another clade with a vestige pedal digit 5, the foot becomes plantigrade, according to PILs analysis.

Pedal digit 5 is sometimes hard to find. Often it is found beneath the metatarsus.  Other times it may become disarticulated and ignored or unsought by preparators, who “know” that all “pterodactyloids” lose pedal digit 5 or have vestiges at best. As you can see above and in more detail at ReptileEvolution.com, the pattern of reduction and enlargement of pedal digit 5 in pterosaurs is a little more complicated than the conventional thinking suggests.

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.

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 2011. A Catalog of Pterosaur Pedes for Trackmaker Identification. Ichnos 18(2):114-141. http://dx.doi.org/10.1080/10420940.2011.573605
Wellnhofer P 1970. Die Pterodactyloidea (Pterosauria) der Oberjura-Plattenkalke Süddeutschlands. Abhandlungen der Bayerischen Akademie der Wissenschaften, N.F., Munich 141: 1-133.
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.