First African pterosaur trackway (manus only)

FIgure 1. From Masrour et al. 2017, manus only pterosaur tracks. They are BIG!

FIgure 1. From Masrour et al. 2017, manus only pterosaur tracks. They are BIG! Again I will note, only lepidosaurs can bend their lateral metacarpophalangeal joints within the palmar plane at right angles to the others, producing posteriorly oriented manual digit 3.

Masour et al. 2017
bring us new manus only Late Cretaceous azhdarchid tracks. They report, “The site contains only manus tracks, which can be explained as a result of erosion of pes prints.” They assume that the pterosaur fingers pressed deeper, carrying more weight on the forelimbs. Of course, this is a bogus explanation. No tetrapods do this. Pterosaurs put LESS weight on their tiny fragile fingers. They used their hands like skiers used ski poles.

FIgure 2. From Masrour et al. 2017, model of the trackmaker of the manus only tracks.

FIgure 2. From Masrour et al. 2017, model of the trackmaker of the manus only tracks erroneously attributed to Bennett 1997, who drew Pterodactylus, not this generalized azhdarchid.

There is another explanation for manus only tracks
called floating and poling, but that hypothesis was dismissed by the authors.

Masrour et al. dismiss the possibility of floating
by referencing Hone and Henderston 2014 in which simulations of the buoyancy of poorly constructed pterosaurs made using computers indicate that these reptiles had no ability to float well in water. This hypothesis was dismantled earlier here. In addition, Hone’s track record is not good. Neither is Henderson’s, who does not seem to care about using accurate skeletal reconstructions.

More importantly,
if Hone and Henderson put forth an anti-floating hypothesis no one (and certainly no scientist) should simply believe in it. This is Science. Others, like Masrour et al., should TEST hypotheses for validity, as was done here. Instead Masrour et al. put forth a hypothesis in which pes tracks were selectively erased over time, which seems preposterous and unnatural. This sort of selective erasure has never been observed in Nature.

Figure 1. The azhdarchid pterosaur Quetzalcoatlus floating and poling producing manus only tracks.

Figure 3. The azhdarchid pterosaur Quetzalcoatlus floating and poling producing manus only tracks. Remember the skull is as light as a paper sculpture.

Scientists fail
when they blindly follow bad hypotheses, just because they are published. Nodding journalists repeat what they read, whether right or wrong. Scientists test whenever they can.

Figure 5. Tapejara poling while floating, producing manus-only tracks, all to scale.

Figure 4. Tapejara poling while floating, producing manus-only tracks, all to scale. Remember the skull is as light as a paper sculpture.

Don’t believe in Henderson cartoons
(Fig. 5). Test with accurate representatives of skeletons IFig. 4).

Computational models of two pterosaurs from Hone and Henderson 2013. Note how both have trouble keeping their nose out of the water. Henderson's models have shown their limitations in earlier papers.

Figure 5. Computational models of two pterosaurs from Hone and Henderson 2013/2014. Note how both have trouble keeping their nose out of the water. Henderson’s models have shown their limitations in earlier papers.

When you don’t use cartoons for data
then you have a much better chance of figuring out how Nature did things.

Figure 4. Two configurations for Rhamphorhynchus. Because the wings act like pontoons, the torso and skull can be rotated relative to the wings to adopt a variety of floating configurations. Also note the large webbed feet, preserved in the darkling specimen. The tail can be elevated at its base.

Figure 6. Two configurations for Rhamphorhynchus. Because the wings act like pontoons, the torso and skull can be rotated relative to the wings to adopt a variety of floating configurations. Also note the large webbed feet, preserved in the darkling specimen. The tail can be elevated at its base.


Thank you for your continuing interest.
After over 2000 blog posts the origin of bats continues to be the number one blog post visited week after week, with totals equalling the sum of the next five topics of interest. That’s where the curiosity of the public is right now.

References
Hone DWE, Henderson DM 2014. The posture of floating pterosaurs: Ecological implications for inhabiting marine and freshwater habitats. Palaeogeography, Palaeoclimatology, Palaeoecology 394:89–98.
Masrour M et al. (4 other authors) 2017. 
Anza palaeoichnological site. Late Cretaceous. Morocco. Part I. The first African pterosaur trackway (manus only). Journal of African Earth Sciences (in press) 1–10.

 

https://pterosaurheresies.wordpress.com/2013/12/06/pterosaurs-were-unlikely-floaters-hone-and-henderson-2013/

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Earliest Cretaceous pterosaur tracks from Spain

Pascual-Arribas  and Hernández-Medrano 2016
describe new pterosaur ichnites from La Muela, near Soria, Spain.

From the abstract
“Pterosaurs tracks in the Cameros basin are plentiful and assorted. This fact has allowed to define several Pteraichnus ichnospecies and moreover to distinguish other morphotypes. The study of the new tracksite of La Muela (Soria, Spain) describes Pteraichnus cf. stokesi ichnites that is an unknown ichnospecies until now and that confirms the wide diversity of this type of tracks in the Cameros Basin. Their characteristics correspond to the ones of the Upper Jurassic track sites of United States. Similar tracks have already been described in other tracksites, both inside and outside the Iberian Peninsula during the Upper Jurassic-Lower Cretaceous transit. Because of their shape and morphometrical characteristics they can be related to the pterosaurs of the Archaeopterodactyloidea clade. The analysis of this ichnogenus indicates the need for a deep review because encompasses ichnites with a big variety of shapes and morphometric characteristics.”

Figure 1. La Muela pterosaur manus and pes tracks, plus tracing and sister ichnotaxa among basalmost ctenochasmatids.

Figure 1. La Muela pterosaur manus and pes tracks, plus tracing and sister ichnotaxa among basalmost ctenochasmatids. Note the extreme length of manus digit 1. This may result from secondary and further impressions during locomotion. Such an extension is no typical. Ctenochasmatids have shorter fingers and claws.

By adding the traits of the La Muela track
to the large pterosaur tree (LPT, 233 taxa) it nested precisely between stem ctenochasmatids and basalmost ctenochasmatids.

Why guess when a large database already exists?
That’s why I published the pterosaur pes catalog with Ichnos in 2011.

Those manus tracks are rather typical for pterosaurs.
Impossible for archosaurs. Typical for lepidosaurs, which have looser metacarpophalanageal joints.

Pascual-Arribas and Hernandez-Medrano
draw triangles, Y-shapes and rectangles around Ctenochasma, azhdarchid and Pterodaustro tracks. Since the triangle and rectangle taxa are sisters, this nearly arbitrary geometrical description is of little phylogenetic use. Ctenochasmatids can spread and contrast their metatarsals, so they can change their pes from one ‘shape’ to another.

A second paper on Spanish ptero tracks
by Hernández-Medrano et al. 2017 describe more tracks. In the first paper, some pterosaur pedes were correctly attributed to Peters 2011. The same illustrations in the second paper were attributed to the authors of the first paper. :  )

References
Hernández-Medrano N, Pascual-Arribas C and Perez-Lorente F 2017. First pterosaur footprints from the Tera Group (Tithonian–Berriasian) Cameros Basin, Spain. Journal of Iberian Geology DOI 10.1007/s41513-017-0020-8. (in English)
Pascual-Arribas C and Hernández-Medrano N 2016. Huellas de Pteraichnus en La Muela (Soria, España): consideraciones sobre el icnogénero y sobre la diversidad de huellas de pterosaurios en la Cuenca de Cameros. (Pteraichnus tracks in La Muela (Soria, Spain): considerations on the ichnogenus and diversity of pterosaur tracks in the Cameros Basin.) Revisita de la Sociedad Geologica de España 29(2):89–105. (in Spanish)
Peters D 2011. A catalog of pterosaur pedes for trackmaker identification. Ichnos, 18: 114–141.

 

Early Triassic turtle tracks and the Permian pareiasaur origin of turtles

From the Lichtiga et al. 2017 abstract:
“Turtle (Testudines) tracks, Chelonipus torquatus, reported from the early Middle Triassic (Anisian) of Germany, and Chelonipus isp. from the late Early Triassic (Spathian) of Wyoming and Utah, are the oldest fossil evidence of turtles, but have been omitted in recent discussions of turtle origins. Recent literature on turtle origins has focused entirely on the body fossil record to the exclusion of the track record.”

Turtle tracks are distinct 
because they appear to walk on their lateral four unguals with little to no heel impression. Images here.

Figure 1. Chronology of Triassic turtle tracks and trackmakers.

Figure 1. Chronology of Triassic turtle tracks and trackmakers from Lichtiga et al 2017. Blue taxa are added here from the LRT. Yellow taxa are ‘turtle’ tracks. The post-crania of Elginia is the big question. Pappochelys is not related to turtles, but Lichtiga et al. included it.

Unfortunately
Lichtiga et al. did not reference the large reptile tree (LRT, 2027 taxa) which nests Pappochelys with placodonts, apart from turtles arising from Sclerosaurus, Elginia, Bunostegos and other pareiasaurs, all descending from Stephanospondylus in the Early Permian.

Even so,
the turtle tracks in the Lower and Lower Middle Triassic indicated to Lichtiga et al. that turtles arose from pareiasaurs based on the similarity of their tracks. They wrote,  Chelonipus also resembles the Permian track Pachypes dolomiticus, generally assigned to a pareiasaur trackmaker.”

So that takes us back
to the odd pareiasaur Bunostegos, the mini pareiasaur/basal turtle Elginia and the not widely recognized basal turtle, Meiolania at the transition to dome-shelled turtles (Fig. 1).

Figure 1. Hard shell turtle evolution with Bunostegos, Elginia, Meiolania and Proganochelys.

Figure 1. Hard shell turtle evolution with Bunostegos, Elginia, Meiolania and Proganochelys.

You might remember
that not only does Meiolania (Fig. 2) most closely resemble and nests with toothy Elginia (Fig. 2), but Meiolania is also the only dome-shelled turtle that can extend its forelimbs laterally. All others, including sea turtles, extend the humerus anteriorly.

Among so-called soft-shelled turtles
and their ancestors, Sclerosaurus, Odontochelys and to a lesser extent, Trionyx can/could also extend the humerus laterally.

Figure 1. The basal turtle, Niolamia, compared to the toothed pareiasaur/turtle?, Elginia. We have no post-crania for Elginia. Figure 1. The basal turtle, Niolamia, compared to the toothed pareiasaur/turtle?, Elginia. We have no post-crania for Elginia.

Figure 2. The basal turtle, Niolamia, compared to the toothed pareiasaur/turtle?, Elginia. We have no post-crania for Elginia.

The Lichtiga et al. paper confirms
all earlier studies that link pareiasaurs and turtles, including the LRT at ReptileEvolution.com —and it helps invalidate all other bogus turtle origin hypotheses.

References
Lichtiga AJ, Lucas AJ, Klein H and Lovelace DM 2017. Triassic turtle tracks and the origin of turtles.Historical Biology, 2017 online

More on those fascinating Middle Devonian tetrapod tracks

Surprisingly,
Middle Devonian tetrapod tracks (Fig. 1; Niedźwiedzki et al. 2010)  precede fossil taxa that could have made those tracks by tens of millions of years.

Wide-gauge 385 million year old tracks from Valentia
could only have been made by a tetrapod with laterally extended limbs found in 360 million year old strata, 25 million years later.

Figure 1. From Niedźwiedzki et al. 2010 showing the Valentia track (above), the Zalchemia track (below) and possible trackmakers (middle). Pink lines link corresponding forelimb and hind limb in the Zalchemia track.

Figure 1. From Niedźwiedzki et al. 2010 showing the Valentia track (above), the Zalchemia track (below) and possible trackmakers (middle). Pink lines link corresponding forelimb and hind limb in the Zalchemia track. Note the wide gauge of the Valentia track versus the narrow gauge of the earlier Zalchemie track.

Narrow-gauge older tracks from Zalchemie
(387 million years ago) also had a shorter stride on a longer torso, matching tetrapods without long lateral limbs, but with short stubs or limbs, like Tiktaalik appearing 12 million years later.

Figure 2. Chronology of Devonian stem tetrapod taxa and trackways. Frame one shows traditional tree without tracks. Frame two extends ghost lineages to consider the tracks as evidence of undiscovered fossils. Fossils represent rare discoveries typically long after major radiations to millions of individuals, increasing the odds of their being found.

Figure 2. Chronology of Devonian stem tetrapod taxa and trackways. Frame one shows traditional tree without tracks. Frame two extends ghost lineages to consider the tracks as evidence of undiscovered fossils. Fossils represent rare discoveries typically long after major radiations to millions of individuals, increasing the odds of their being found.

The problem is
the wider tracks come from an era in which Tiktaalik-like taxa are known as fossils, some 25 million years too soon based on fossil taxa like Ichthyostega, (Fig. 3).

Figure 3. Best Devonian Valentia track with various overlays.

Figure 3. Best Devonian Valentia track with various overlays.

The solution is
fossils of all sorts can be discovered close to the genesis of a clade, but are more likely to be discovered close to the maximum radiation (in terms of numbers of individuals), increasing the odds for preservation and discovery. Applying logic here, the skeletons must be appearing near the maximum radiation while the ichnites must be appearing near the genesis of the clade. But wait, there’s more:

Figure 5. Various stem amniotes (reptiles) that precede Tulerpeton in the LRT. So these taxa likely radiated in the Late Devonian. And taxa like Acanthostega and Ichthyostega are late-survivors of earlier radiations documented by the earlier trackways.

Figure 5. Various stem amniotes (reptiles) that precede Tulerpeton in the LRT. So these taxa likely radiated in the Late Devonian. And taxa like Acanthostega and Ichthyostega are late-survivors of earlier radiations documented by the earlier trackways.

The taxa listed above
(Fig. 5) all precede Latest Devonian Tulerpeton in the large reptile tree (LRT, 1027 taxa), though their first appearance in the fossil record occurs much later in every case. That must mean the genesis of the various radiations that produced these taxa must have occurred in the Late Devonian. Currently that’s heresy. But that’s where the current evidence leads us. At present these clues tell us where to look in the geological column and what to look for.

And for all you future paleontologists:
there’s a great paper waiting for the next person or team to find these pre-Tulerpeton taxa in Late Devonian strata. Based on the stress to living things that occurred during the Latest Devonian extinction event, perhaps these taxa radiated quickly and widely.

References
Niedźwiedzki G, Szrek P, Narkiewicz K, Narkiewicz M and Ahlberg PE 2010. Tetrapod trackways from the early Middle Devonian period of Poland Nature 463, 43-48. doi:10.1038/nature08623

What made those Early Triassic tracks?

Mujal et al. 2017
reported on an Early Triassic tracksite dominated by what they considered to be ‘archosauromorph’ trackmakers (Fig. 1), akin to coeval Euparkeria (Fig. 2).

Figure 1. Early Triassic tracks from Mujal et al. 2017 compared to Didelphis, the extant Virginia opossum to scale. I don’t see any lateral expansion due to a hooked metatarsal (as in Fig. 2) here.

Unfortunately, the track in question
identified as Prorotodactylus mesaxonichnus IPS-93867 had three long slender digits (2–4), about the same length, #2 a stitch shorter. #1 and #5 much shorter. The width is about 2 cm. The pes is much larger than the manus. All in all, it is close to the shape and size of Didelphis, the extant, but very ancient Virginia opossum (Fig. 1). Originally the track was assigned to a taxon near Euparkeria, and it’s a pretty good match, but there is no indication of a hooked metatarsal 5 and digit 3 is often the longest (BUT see below).

Figure 2. Euparkeria pes.

Figure 2. Euparkeria pes is similar in size and configuration to the Early Triassic trackmaker. Note the hooked lateral metatarsal (#5) and digit #3 the longest.

Among archosauriformes
in proterosuchids and Garjainia pedal digit 4 is the longest. Some chorisoderes retain this pattern. In some 3 and 4 are the longest. In Champsosaurus 3 is the longest. Similar patterns are found in phytosaurs. In basal proterochampsids digit 3 is the longest. In derived proterochampsids like Tropidosuchus and Lagerpeton digit 4 is not slender and it is the longest in the series. None are matches for the

Among euarchosauriformes
In Euparkeria, as in most euarchosauriformes, digit 3 is longer than 2 and 4 and much longer than 1 and 5. In erythrosuchids pedal digits 2 and 3 are slightly longer than 4, but all are short and large. Ornithosuchus has long toes and short fingers, but it is a much larger taxon. Pedal digit 3 is still the longest. Same with Qianosuchus and Ticinosuchus.

Among basal diapsids and enaliosaurs
the pes is typically asymmetric with digit 4 or digits 3 and 4 the longest. The same with lepidosaurs. Basal lepidosauromorphs have short digits.

Basal synapsids are no match, either.
because they, too, have asymmetric feet. That changes with therapsids, but most have short toes, similar sized manus and pes and are Permian in age. That changes with the pre-mammals, the tritylodontids, like Spinolestes, which extend into the Cretaceous. The only problem with many of the trackmakers with symmetrical pedes, they all had narrow-gauge trackways – distinct from the Early Triassic trackways, which are quite wide-gauge. We can’t discuss mammals, because they only developed in the Late Triassic, at the earliest.

There’s one more factor
To me it looks like the tracksite toes are webbed. If the trackmaker was mostly aquatic, it was more likely to have sprawling hind limbs.

So, in summary
the best match in terms of size, relative size, age, morphology and such… appear to be aquatic Early Triassic tritylodontids… or tiny unknown archosauromorphs somewhere between Proterosuchus and Euparkeria. That hypothetical taxon would have had a pes transitional between the long digit 4 of Proterosuchus and the long digit 3 of Euparkeria. I really could not find a better match for this tracksite maker. I could not nail it down with available candidates.

References
Mujal E, Fortuny J, Bolet A, Oms O, López JA 2017. An archosauromorph dominated ichnoassemblage in fluvial settings from the late Early Triassic of the Catalan Pyrenees (NE Iberian Peninsula). PLoS ONE 12(4): e0174693. https://doi.org/10.1371/journal.pone.0174693

Is this the footprint of Arizonasaurus?

Figure 1. Synaptichnium MNA V3425. Arrow points to direction of movement and aligns with sagittal plane. PILs and pads added.

Figure 1. Synaptichnium MNA V3425. Arrow points to direction of movement and aligns with sagittal plane. PILs and pads added. The pink manus track is another specimen.

The middle Triassic Moenkopi formation
in Arizona has provided a rich trove of fossils. An excellent footprint (MNA V3425, Fig. 1) was recently published online here and attributed to Arizonasaurus, a likely bipedal carnivorous archosauriform (Fig. 2). Arizonasaurus was derived from basal Rauisuchia, like Vjushkovia, and is most closely related to Yarasuchus and Qianosuchus according to the large reptile tree.

Figure 2. Arizonasaurus. Not sure which of the two mandibles is correct here, so both are presented. Note, neither manus nor pes is preserved in the specimen.

Figure 2. Arizonasaurus. Not sure which of the two mandibles is correct here, so both are presented. Note, neither manus nor pes is preserved in the specimen.

According to the online article,
“Paleontologist Christa Sadler has written a book, “Dawn of the Dinosaurs,” about the archosaurs of the Middle and Late Triassic in the region. Unusually detailed footprints of the large reptile, or something like it, are preserved in a slab of Moenkopi sandstone in the collections repository at the Museum of Northern Arizona, where Sadler has studied. MNA  [Museum of Northern Arizona] Colbert Collections Curator of Vertebrate Paleontology David Gillette, Ph.D., says the footprints were discovered in Wupatki National Monument in 1973.”

Figure 3. Manus impression of man v3245. Note the heavy scales here.

Figure 3. Manus impression of man v3245. Note the heavy scales here.

The LRT currently doesn’t include ichnites (footprints)
but let’s see what happens this time, since the track is so precisely imprinted. Unfortunately, Arizonasaurus does not preserve the manus or the pes (Fig. 1). Nevertheless, out of 801 candidate taxa, MNA 3425 nests with a sister to Arizonasaurus, Decuriasuchus, and is similar to the pes of other Arizonasaurus sisters, Qianosuchus and Nandasuchus, all Middle Triassic taxa. So, phylogenetic bracketing works, at least to this extent. And it just shows you don’t need a long list of character traits to successfully nest some taxa.

Figure 3. Scaly palms of two crocodilians. Digit 1 is on the left in both specimens.

Figure 4. Scaly palms of two crocodilians. Digit 1 is on the left in both specimens.

Notes on the scaly palm of MNA V3425
Dinosaur footprints do not have large scale impressions. By contrast, croc hands and feet do have large scales (Fig 3). The sisters to Arizonasaurus, Qianosuchus and Yarasuchus, both have short limbs, a long rostrum and a general crocodile-like build. Likewise Decuriasuchus was long-bodied, quadrupedal with a large foot and a presumably small hand (not preserved). In similar fashion, Arizonasaurus likely also had a large foot and small hand based on its pectoral and pelvic girdles and femur (Fig. 2), but was a likely biped.

Figure 5. Decuriasuchus does not preserve the manus, but it was probably small based on the forelimb.

Figure 5. Decuriasuchus does not preserve the manus, but it was probably small based on the forelimb.

Belated apologies
to those who tried [or continue to try] to access www.reptileevolution.com yesterday and today. Eviidently the server is down, wherever it is. I can’t access it either to make updates and repairs. Hopefully the RepEvo website will be restored soon. :  )

 

Not Arizonasaurus, but Postosuchus, made the giant Isochirotherium tracks

A recent paper by Diedrich (2015) purported to match the Arizonasaurus to giant Isochirotherium tracks from the Middle Triassic of Germany (Fig. 1).

The problem is,
no manus or pes are known for Arizonasaurus. Furthermore, all related taxa in the large reptile tree have digit 3 the longest, and all digits are elongate. The giant Isochirotherium tracks indicate that both digits 2 and 3 are the longest, and they are short. So matching candidates have to be found elsewhere, not close to Arizonoasaurus (although the size and time are right!).

Among the 504 taxa in the large reptile tree that are possible candidates with digits 2 and 3 the longest are Erythrosuchus (Fig. 1), Shansisuchus, Lotosaurus and the Postosuchus alisonae (Peyer 2008, Fig. 1). It turns out that only the latter is the best match when scaled up to the size of P. kirkpatrchicki (Chatterjee 1985, Fig. 1).

Figure 1. Giant Isochirotherium tracks matched to Postosuchus alisonae scaled up to the size of P. kirkpatrcki.

Figure 1. Giant Isochirotherium tracks matched to Postosuchus alisonae scaled up to the size of P. kirkpatrcki. Click to enlarge. This taxon was not considered originally because it is Late Triassic and the tracks are Middle Triassic.

Postosuchus was not mentioned in the text
because Diedrich (recent email) knew Postosuchus was Late Triassic, not Middle Triassic. He did not accept the idea that between the origin, radiation and extinction of Postosuchus there might have been a Middle Triassic relative.

Diedrich also saw the small manus tracks and assumed they were produced by a large poposaurid. Unfortunately, Arizonasaurus does not nest with poposaurids either. And poposaurids, other than Lotosaurus, do not match the track morphology.

It would have been helpful,
I suppose, to do what I did and make a list of possible candidates from a large list, AND THEN delete the possible candidates one by one as bad matches. Other than that phylogenetic bracketing mismatch, Diedrich does good work with excellent graphics. It took a leap of faith, I suppose to match tracks to a taxon for which no manus or foot is known.

C. Diedrich writes:
“Watch my ARTE docu – there you see Arizonasaurus (Ticinosuchus and Macrocnemus) walking in my point of view combining trak/sleketal records”:http://www.youtube.com/watch?v=b9GcVmb6OtE

References
Chatterjee S 1985. Postosuchus, a new Thecodontian reptile from the Triassic of Texas and the origin of Tyrannosaurs. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences 309 (1139): 395–460. doi:10.1098/rstb.1985.0092.
Diedrich C 2015.
Isochirotherium trackways, their possible trackmakers (?Arizonasaurus): intercontinental giant archosaur migrations in the Middle Triassic tsunami-influenced carbonate intertidal mud flats of the European Germanic Basin  Carbonates and Evaporites  DOI 10.1007/s13146-014-0228-z
Novak SE 2004. A new specimen of Postosuchus from the Late Triassic Coelophysis Quarry, siltstone member, Chinle Formation, Ghost Ranch, New Mexico. M.S. thesis, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
Peyer K Carter, JG, Sues H-D, Novak SE, and Olsen PE 2008. A new Suchian Archosaur from the Upper Triassic of North Carolina. Journal of Vertebrate Paleontology 28 (2): 363–381. doi:10.1671/0272-4634(2008)28[363:ANSAFT]2.0.CO;2.