Manual digit 5 on Bellubrunnus (= basal Rhamphorhynchus)

In several phylogenetic predecessors of pterosaurs
such as Cosesauru, Sharovipteryx and Longisquama. manual digit 5 is small but clearly present (Fig. 1). Traditional workers report that manual digit 5 is absent in pterosaurs.

pterosaur wings

Figure 1. Click to enlarge. The origin of the pterosaur wing and whatever became of manual digit 5?

In pterosaurs
I have shown here, here and here several examples of a vestigial manual digit 5 on the axially rotated metacarpal 4. Unfortunately, other workers do not yet recognize these hard to see bones. Heck, they don’t recognize these taxa as pterosaur sister taxa, so we know the similar frustration John Ostrom and John Huxley felt when workers did not accept their bird/dinosaur hypothesis reviewed here.

Bellubrunnus-digit5

Figure 2. Click to enlarge. The carpus and manus of Bellubrunnus identifying element including a vestige of manual digit 5. Yes, it’s tiny, but all vestiges are. Look closely, fellow workers, and you will find it for yourself. U = ulna. Ul = ulnare. R = radius. Ra = radiale. Pt = pteroid. PC = preaxial carpal. Numbers = unfused distal carpals and manual digits.

Hone et al. 2012
provided exquisite UV closeups of the tiny specimen, but did not identify vestigial manual digit 5. I do so here (Fig. 2). It’s clear, but tiny, as most vestiges are.

The carpal elements
are unfused because this adult specimen is the result of phylogenetic miniaturization. It’s ancestors among the genus Campylognathoides, were much larger individuals, as shown here. Essentially Bellubrunnus is a precocious adult, sexually mature in an otherwise immature, reduced size body. This can confuse those who work in bone histology and workers who don’t understand lepidosaur fusion patterns. Phylogenetic analysis, as shown here, solves these problems.

References
Hone DWE, Tischlinger H, Frey E and Röper M. 2012. A New Non-Pterodactyloid Pterosaur from the Late Jurassic of Southern Germany. PLoS ONE 7(7): e39312. doi:10.1371/journal.pone.0039312

 

 

When bipedal archosaurs become aquatic and croc-like

It happened twice.
Some bipedal theropods and bipedal theropod-like archosaurs evolved to become quadrupedal crocs and quadrupedal croc-like theropods.

Most famously and most recently,
Spinosaurus (Fig. 1), long suspected as being a fish-eater, was reconstructed with shorter than expected hind limbs, thus forsaking any ability to walk on its hind limbs alone. Some workers think this chimaera reconstruction is bogus. Others are more accepting. Spinosaurus was derived from bipedal theropods like Suchomimus and Sinocalliopteryx. Deinocheirus was giant frill back bipedal theropod related to Spinosaurus.

Figure 1. Derived from bipedal sisters, giant Spinosaurus had such short hind limbs that it could no longer rise to a bipedal configuration. Not only did it have a croc-like head, it had something approaching a croc-like post-crania (sans the sail, of course).

Figure 1. Derived from bipedal sisters, giant Spinosaurus had such short hind limbs that it could no longer rise to a bipedal configuration. Not only did it have a croc-like head, it had something approaching a croc-like post-crania (sans the sail, of course).

Basal bipedal crocs evolved to become extant quadrupedal crocs
Basal crocs were bipeds (Fig. 2), only later shortening the hind limbs to become quadrupedal, like the theropod dinosaur, Spinosaurus (Fig. 1).

Figure 2. The evolution of extant crocs from primitive bipeds and transitional quadrupeds. One branch led to Protosuchus, the other, along with several side branches, to extant species.

Figure 2. The evolution of extant crocs from primitive bipeds and transitional quadrupeds. One branch led to Protosuchus, the other, along with several side branches, to extant species. Interesting to see that Sphenosuchus has taller dorsal spines than either predecessors or successors.

It’s of mild interest
to note that the transitional croc, Sphenosuchushad taller dorsal spines than either more primitive or more derived taxa (Fig. 2).

It’s of even milder interest
to note the quadrupedal poposaur, Lotosaurus, is derived from a sister to the bipedal poposaur, Poposaurus.

Figure 1. Lotosaurus, a finback poposaur.

Figure 3. Lotosaurus, a finback poposaur.

Contra this pattern,
the finback Arizonasaurus is a likely biped (based on its deep pelvis) derived from quadrupedal, shallow-pelvis, basal rauisuchians, like Vjushkovia. Even so, the closest relatives of Arizonasaurus include croc-like Yarasuchus and Qianosuchus both of whom have semi-tall spines.

Figure 1. Arizonasaurus configured as a biped. The depth of the pubis suggests a similar length for the femur and tibia. The gracile pectoral girdle suggests a gracile forelimb. The long deep tail is based on the related Yarasuchus.

Figure 4. Arizonasaurus configured as a biped. The depth of the pubis suggests a similar length for the femur and tibia. The gracile pectoral girdle suggests a gracile forelimb. The long deep tail is based on the related Yarasuchus.

A relative of Arizonasaurus
by analogy, not homology, is Qianosuchus (Fig. 5). It shares many traits with Spinosaurus, sans the frill.

Figure 4. Qianosuchus shares quite a few traits with Spinosaurus, sans the frill. Qianosuchus has similarly-sized limbs.

Figure 5. Previously unnoticed, the derived rauischian, Qianosuchus, shares many traits with Spinosaurus, sans the frill. Qianosuchus has similarly-sized limbs and a similar long rostrum and neck.

References
Ibrahim N et al. 2014. Semiaquatic adaptations in a giant predatory dinosaur. Science 345 (6204): 1613–6.

 

 

Another look at the tiny pterosaur, Nemicolopterus

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

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

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

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

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

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

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

Figure 3. Two images of Nemicolopterus superimposed and traced with transparent colors. Note, not all of the shapes seen in photo 1 can be seen in photo 2. There appear to be extra tiny bones in the belly of this specimen.

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

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

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

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

wiki/Nemicolopterus

Pregnant hummingbird-like pterosaurs

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

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

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

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

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

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

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

Figure 2. The torso of B St 1967 I 276 (No. 6 of Wellnhofer 1970) showing the pectoral girdle and embryo.

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

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

Figure 4. Two of the smallest pterosaurs that both have a large sternal complex. BMNH42736 and B St 1967 I 276.

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

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

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

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

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

wiki/Pterodactylus

 

 

Marching Dinosaurs Video

Figure 1. Marching dinosaurs video. Click to view.

Figure 1. Marching dinosaurs video. Click to view.

Make sure you see this one.
Click on the pic or here to view. I am very impressed by the accuracy and quantity shown in this video.

And, of course,
I’m a big fan of humans and dinosaurs to scale AND walking videos!

A few days ago
I showed an early term pregnant pterosaur. Just a reminder (because I forgot, too!), that was not the first pterosaur with extra bones inside. Here’s the other one.

Pterodactylus n15 reconstructed using digital graphic segregation (DGS)

The nearly perfect specimen
(plate and counter plate) of the  BSP AS V 29a/b specimen of Pterodactylus (n15 in the Wellnhofer 1970 catalog, Fig. 1) is today’s subject.

Figure 1. Click to enlarge. The plate and counter plate of the BSP AS V 29a/b specimen of Pterodactylus with color overlays of the bones and visible soft tissues.

Figure 1. Click to enlarge. The plate and counter plate of the BSP AS V 29a/b specimen of Pterodactylus (n15) with color overlays of the bones and visible soft tissues. Click to enlarge. Now, does not this method improve on just about all others as far as identifying and delineating the skeletal elements? 

DGS
Digital Graphic Segregation has been unfairly maligned by some workers, embraced by others. Here (Fig. 1) is a great example of bone tracing, not only the easy ones on top (left side elements), but also the more difficult ones below (right side elements).

Figure 1. Click to enlarge. The plate and counter plate of  the BSP AS V 29a/b specimen of Pterodactylus with color overlays of the bones and visible soft tissues.

Figure 1. Click to enlarge. The plate and counter plate of the BSP AS V 29a/b specimen of Pterodactylus with color overlays of the bones and visible soft tissues. Click to enlarge.

This specimen appears to have a naris separated from the reduced antorbital fenestra by a stretch of soft tissue, (here colored green, like the maxilla).

Figure 3. Pterodactylus specimen BSP AS V 29a/b, n15 in the Wellnhofer 1970 catalog torso.

Figure 3. Pterodactylus specimen BSP AS V 29a/b, n15 in the Wellnhofer 1970 catalog torso. Yes, there’s a little sternal complex inside all those ribs and gastralia. I don’t see a fetus in this one. Click to enlarge.

 

Yesterday we looked at another specimen of Pterodactylus in which the dorsal and sacral vertebrae of the fetus were visible in ventral view. Those vertebrae looked like a series of tiny bow ties. In the n15 specimen the same pattern is visible due to crushing.

Figure 3. Colored elements of Pterodactylus specimen BSP AS V 29a/b.

Figure 4. Colored elements of Pterodactylus specimen BSP AS V 29a/b. I might not have gotten everything right, but this is more than one usually gets in a published tracing. 

This basic Pterodactylus
had been mistakenly reassigned to Aerodactylus by Vidovic and Martill 2014. Still not sure why considering it nests within Pterodactylus in the large pterosaur tree.

Figure 5. Pterodacatylus specimen BSP AS V 29a/b reconstructed from DGS tracing (fig. 4).

Figure 5. Pterodacatylus specimen BSP AS V 29a/b reconstructed from DGS tracing (fig. 4). Quadrupedal or bipedal, pterosaurs could do it all. 

Considering the width of those gastralia
this pterosaur, like so many others, appears to have had a more flattened (wider) torso than traditionally reconstructed. Now, does not this method improve on just about all others as far as identifying and delineating the skeletal elements?

References
Meyer H 1860. Zur Fauna der Vorwelt: Reptilien aus dem lithographischen Schiefer des Jura in Deutschland und Frankreich. Frankfurt. 1–84.
Vidovic SU and Martill DM 2014. Pterodactylus scolopaciceps Meyer, 1860 (Pterosauria, Pterodactyloidea) from the Upper Jurassic of Bavaria, Germany: The Problem of Cryptic Pterosaur Taxa in Early Ontogeny. PLoS ONE 9(10): e110646. doi:10.1371/journal.pone.0110646

wiki/Pterodactylus

A peek beneath the ribs of Pterodactylus scolopaciceps

A not so recent PLOSOne paper (Vidovic and Martill 2014, Late Jurassic) on Pterodactylus scolopaciceps (Meyer 1860, BSP 1937 I 18 (Broili 1938, P. kochi No. 21 of Wellnhofer 1970, 1991) provided the images seen here (Figs. 3, 4). It is one of the best preserved pterosaurs of all. Earlier we critically examined Vidovic and Martill 2014 here. A few short notes and images (Figs. 1,2) below will summarize those criticisms. Otherwise, the photos bring today’s news: tracings of the overlooked coracoids, sternal complex and an early embryo (Figs. 4, 5).

Vidovic and Martill reported,
“The majority of pterosaur species from the Solnhofen Limestone, including P. scolopaciceps are represented by juveniles.” This is utter rubbish.  Several hummingbird- to sparrow-sized adults, yes! …and some with long rostra! …but no verifiable juveniles, EXCEPT the juvenile of the giant Rhamphorhynchus recovered and described here. Remember, pterosaur embryos and juveniles are close matches to their parents as they develop isometrically, able to fly upon hatching, not allometrically. The large pterosaur tree demonstrates the phylogenetic miniaturization is what saved certain pterosaur lineages from extinction following a great radiation in the Late Jurassic. This is evidence Vidovic and Martill refuse to accept.

Vidovic and Martill continue:
“Consequently, specimens can appear remarkably similar due to juvenile characteristics detracting from taxonomic differences that are exaggerated in later ontogeny.” More rubbish based on adherence to Bennett (1996, 1996. 3006) who synonimized dozens of Solnhofen specimens without so much as an attempt at phylogenetic analysis, which lumps and separates the lot into individual taxa here. The Vidovic and Martill cladogram includes only 33 taxa (10 from Solnhofen) and lumps several pterosaurs successfully together (tapejarids, ctenochasmatids, pteranodontids), but fails to put these clades correctly into large clades, nesting sharp beak toothless taxa with broad beak toothy taxa, etc. etc.

Vidovic and Martill dig themselves deeper
“A hypodigm for P. scolopaciceps, comprising of the holotype (BSP AS V 29 a/b) and material Broili referred to the taxon is described. P. scolopaciceps is found to be a valid taxon, but placement within Pterodactylus is inappropriate. Consequently, the new genus Aerodactylus is erected to accommodate it.” As you can see (Figs. 1, 2) and as has been tested, placement within Pterodactylus (Fig. 2)  is MORE appropriate than nesting with purported sisters promoted by Vidovic and Martill (Fig. 1).

Figure 4. Sister taxa of "Aerodactylus" according to Vidovic and Martill 2014 include Gladocephaloides and Cycnnorhamphus. More rubbish.

Figure 1. Sister taxa of “Aerodactylus” according to Vidovic and Martill 2014 include Gladocephaloideus and Cycnnorhamphus. More rubbish. Neither are even related to one another as the former is a ctenochasmatid and the latter, of course, is a cycnohrmphid. Click to enlarge.

Evolution works in minute steps
and the more traits shared between specimens, both overall and in minute detail, the more closely they are related. Vidovic and Martill may also be working under the false assumption that pterosaurs are archosaurs and follow archosaur fusion patterns. No. Pterosaurs are lepidosaurs and follow lepidosaur fusion patterns, which are largely phylogenetic, not ontogenetic, as reported earlier.

Figure 3. Click to enlarge. The large pterosaur tree nests these three taxa together. So this Pterodactylus really is a Pterodactylus.

Figure 2. Click to enlarge. The large pterosaur tree nests these three taxa together. So this Pterodactylus (BSP AS V 28a/b) really is a Pterodactylus (contra Vidovic and Martill)

 

Enough about that paper.
I was drawn to this specimen (Fig. 3) because I did not have data for the coracoids and took another look for them with this excellent photo.

Figure 1. Pterodactylus scolpaciceps from Vidovic and Martill 2014 with elements below the ribs traced in color.

Figure 3. Pterodactylus scolpaciceps from Vidovic and Martill 2014 with elements below the ribs traced in color. Soft tissue is persevered in this specimen, and so is an embryo.

Lo and behold
the coracoids and sternal complex were visible as impressions (Figs. 3, 4) and there was something else further back… an embryo. Not full term. Not fully ossified. The wings are invisible or lost among the ribs and gastralia. Unlike 3D eggs, crushed fossils lay out all the elements into a single bedding plane.

Figure 2. Closeup of the torso of Pterodactylus scolopaciceps showing the coracoids, sternal complex and a passenger.

Figure 4 Closeup of the torso of Pterodactylus scolopaciceps showing the coracoids, sternal complex and a passenger. I was drawn to revisit this specimen because I lacked data for the length of the coracoids. This excellent image provided that data and possibly more. The bones of the embryo are not fully ossified yet. The shell is not formed. Those happen closer to the time just before egg-laying.

The embryo 
is the right size, shape and morphology to someday pass through the pelvis. The bones are soft and underdeveloped. No trace of an eggshell is apparent, but that’s not supposed to happen until the last stages of gestation.

Figure 4. Pterodactylus scolopaciceps reconstructed with the passenger shown here expelled. It is the right size, shape and morphology to be an embryo within an egg.

Figure 5. Pterodactylus scolopaciceps reconstructed with the passenger shown here expelled. It is the right size, shape and morphology to be an embryo within an egg.

Unlike archosaurs
lepidosaurs carry their young for longer terms, sometimes to the point of live birth (viviparity). Earlier I proposed that pterosaurs, like some of their sister lepidosaurs, carried their embryos until just prior to hatching. Other workers, all of whom consider pterosaurs archosaurs, thought egg burial was their method of reproduction. Not sure how they imagine a fragile pterosaur with tearable wing membranes would manage to dig through whatever dirt, sand or debris they were buried in. The aborted egg of Darwinopterus similarly contains an immature and unossified embryo. We also have an aborted fetus in Anurognathus and an aborted egg in the tiny pterosaur, Ornithocephalus added to the Pterodaustro embryo, the ornithocheirid embryo (revised recently) and the (relatively) giant, proto-anurognathid embryo.

How many pterosaur fossils are pregnant?
If they are doing their job, half of the adults should be pregnant, unless females greatly outnumber males, then that percentage goes up. Very few, however, will be preserved with late stage embryos that preserve even impressions of bones. As everyone knows the thinnest bone walls in the animal kingdom are pterosaur bones, thinner yet in embryos and  softer yet in younger embryos.

It’s time people
It’s time to let go of those old paradigms about pterosaur origins, wing shape and interrelationships. Those old hypotheses are not working. They cannot be verified. They are the stuff of myth. I would hate to think that these workers are refereeing manuscripts.

Carl Sagan said this about letting go of old paradigms,
“The essence of the Scientific method is the willingness to admit your’re wrong, to abandon ideas that don’t work, and the essence of religion is not to change anything, that supposed truths are handed down by some revered figure and no one is to make any progress beyond that because all the truth is thought to be in hand.”

References
Bennett SC 1995. A statistical study of Rhamphorhynchus from the Solnhofen Limestone of Germany: Year-classes of a single large species. Journal of Paleontology 69:569-580.
Bennett SC 1996. Year-classes of pterosaurs from the Solnhofen limestone of Germany: Taxonomic and systematic implications. Journal of Vertebrate Paleontology 16: 432–444.
Bennett SC 2006. Juvenile specimens of the pterosaur Germanodactylus cristatus, with a review of the genus. Journal of Vertebrate Paleontology 26:872–878.
Vidovic SU, Martill DM 2014. Pterodactylus scolopaciceps Meyer, 1860 (Pterosauria, Pterodactyloidea) from the Upper Jurassic of Bavaria, Germany: The Problem of Cryptic Pterosaur Taxa in Early Ontogeny. PLoS ONE 9(10): e110646. doi:10.1371/journal.pone.0110646