Revisiting the pes of Pectodens

Earlier we looked at Pectodens, a long-necked tritosaur that nests at the base of the tanystropheids + langobardisaurs and the fenestrasaurs, which ultimately gave rise to pterosaurs.

Metacarpal 5 is the problem (Fig. 1).

Figure 1. The right pes of Pectodens in situ (left), sans the matrix (right), and rearranged to match sister taxa (center). The question is: is the rearrangement valid?

Figure 1. The right pes of Pectodens in situ (left), sans the matrix (right), and rearranged to match sister taxa (center). The question is: is the rearrangement valid?

 

Which bone is metacarpal 5?
Is it the long bone similar to metacarpal 4? That would make sense with most taxa, except Pectodens nests with other long-necked taxa, like Langobardisaurus and Tanystropheus. In those taxa metacarpal 5 is short and pedal 5.1 is metapodial (= very long).

Did taphonomy change things?
Or do we trust phylogenetic bracketing?

One more thing…
If the long bone is the metacarpal, then the phalangeal count matches sister taxa (4 phalanges). If the short bone is the metacarpal, then there is one extra phalanx. Did the preparator add a bone? Or did this taxon have an extra bone?

And take a look
at the width of the tibia + fibula. It’s the right width if the short bone is metacarpal 5. The width is not quite wide enough if the long bone is metacarpal 5.

Sometimes
you have to make a decision in paleontology. Sometimes you have to point your finger at a preparator’s mistake. Sometimes you make the mistake when you use your brain OR when you accept the data as presented.

What to do… what to do…

Figure 1. Pectodens reconstructed using the original tracings of the in situ fossil in Li et al. 2017.

Figure 2. Pectodens reconstructed using the original tracings of the in situ fossil in Li et al. 2017.

Here’s what I wrote a while back
at ReptileEvolution.com:

Pectodens zhenyuensis (Li et al. 2017; IVPP V18578; Anisian, Middle Triassic; 38cm in length) was originally considered to be a diapsid and a possible protorosaur. Here Pectodens nests between Macrocnemus and Langobardisaurus. Originally the interclavicle, sternum and quadratojugal were overlooked. Note the large orbit, the long metarsal 5 and the perforated pubis. The elongate caudal transverse processes anchor powerful leg muscles.

Figure 2. Pectodens skull traced using DGS techniques and reassembled below.

Figure 3. Pectodens skull traced using DGS techniques and reassembled.

With the short metacarpal 5
Pectodens cleanly nests with fewer autapomorphies at the base of the Langonbardisaurus/Tanystropheus clade.

References
Li C, Fraser NC, Rieppel O, Zhao L-J and Wang L-T 2017. A new diapsid from the Middle Triassic of southern China. Journal of Paleontology.7 pp. doi: 10.1017/jpa.2017.12

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Roadrunner skull and surface features

These two images of the extant roadrunner
(Fig. 1; genus: Geococcyx) were so close to each other, they presented a great opportunity to match skull to surface features on one of our favorite birds.

Figure 1. GIF animation of Geococcyx skull matched to surface feathers. Distinct from other birds tested so far, the nares is far forward, apart from the antorbital fenestra.

Figure 1. GIF animation of Geococcyx skull matched to surface feathers. Distinct from other birds tested so far, the nares is far forward, apart from the antorbital fenestra.

A minimum of guesswork
and/or imagination was used in the creation of this image. Since the skull is a cast, sutures were ‘sutured’ to create a single object.

Geococcyx californum 
(Wagler 1831; up to 60 cm longl) the extant roadrunner is a small terrestrial heron and a basal neognath with a posteriorly rotated pedal digit 4, unrelated to parrots and toucans with a similar toe. Traditionally roadrunners are considrered part of the cuckoo family. When cuckoos get tested, they may also nest here. They have shorter hind legs.

Figure 2. Geococcyx the roadrunner skeleton. Note the crane-like proportions of this small land heron.

Figure 2. Geococcyx the roadrunner skeleton. Note the crane-like proportions of this small land heron, probably a late-surviving Early Cretaceous member of the Euornithes.

And where does the roadrunner nest
in the large reptile tree (LRT 1087 taxa)? Between toothy Yanornis and toothless Ardea, the heron, all three at the base of the neognath birds, not surprisingly close to Sagittarius and Cariama, two other extant bird terrestrial predators with long hind limbs.

Nullius in verba

References
Wagner JG 1831. Einige Mitheilungen über Thiere Mexicos. Oken’s Isis 24:510–535.

wiki/Roadrunner

A fresh reconstruction of Pelagornis nests it with Macronectes

Updated October 12, 2017 with a longer maxilla and a shorter mandible and a new nesting. 

Pelagornis chilensis (Lartet 1857, Mayr and Rubilar-Rogers 2010; Miocene; MNHN SGO.PV 1061; Fig. 1) is an extinct giant soaring bird here related to Macronectes, the giant Southern petrel (Fig. 2). Bony, not true teeth, developed along the jaw margins. The external naris was divided by bone.

Mayr and Rubilar-Rogers reported,
“We finally note that the phylogenetic affinities of bony-toothed birds still have not been convincingly resolved.” I made a fresh reconstruction (Fig. 1) and tested it against a long list of Cretaceous and post-Cretaceous birds to see where it nests.

FIgure 1. Pelagornis, new reconstruction of skull along with overall reconstruction from Mayr and Rubilar-Rogers

FIgure 1. Pelagornis, new reconstruction of skull along with overall reconstruction from Mayr and Rubilar-Rogers

Pelagornis is an earlier larger version of
the large soaring sea birds, the petrels (Figs. 2, 3), not far from New World vultures.

Figure 5. Macronectes, the Southern giant petrel, in vivo.

Figure 2. Macronectes, the Southern giant petrel, in vivo.

Figure 3. Macronectes giganteus, the extant Southern giant petrel.

Figure 3. Macronectes giganteus, the extant Southern giant petrel. Note the long maxilla. 

My earlier error was realized
when birds with long maxillae, like Macronectes, starting appearing in the LRT.

References
Lartet E 1857. Note sur un hum´erus fossile d’oiseau, attribu ´e `a un tr `es-grand palmip`ede de la section des Longipennes. Comptes rendus hebdomadaires des S´eances de l’Acad´emie des Sciences (Paris) 44:736–741.
Mayr G and Rubilar-Rogers D 2010. Osteology of a new giant bony-toothed bird from the Miocene of Chile, with a revision of the taxonomy of Neogene Pelagornithidae. Journal of Vertebrate Paleontology 30(5):1313-1340.

wiki/Pelagornis

Versperopterylus (Lü et al. 2017) did not have a reversed first toe

And this specimen PROVES again
that anurognathids DID NOT have giant eyeballs in the anterior skull.

Figure 1. Vesperopterylus in situ. There is nothing distinct about pedal digit 1.

Figure 1. Versperopterylus in situ. There is nothing distinct about pedal digit 1.

Lü et al. 2017 bring us a new little wide-skull anurognathid
Versperopterylus lamadongensis (Lü et al. 2017) is a complete skeleton of a wide-skull anurognathid. It was considered the first pterosaur with a reversed first toe based on the fact that in digit 1 the palmar surface of the ungual is oriented lateral while digis 2–4 the palmar surfaces of the unguals are medial. That is based on the slight transverse curve of the metatarsus (Peters 2000) and the crushing which always lays unguals on their side. In life the palmar surfaces were all ventral and digit 1 radiated anteriorly along with the others.

Figure 2. Vesperopterylus reconstructed using original drawings which were originally traced from the photo. Manual digit 4.4 is buried beneath other bones and reemerges to give its length. Pedal digit 1 turns laterally due to metacarpal arcing and taphonomic crushing. There is nothing reversed about it. 

Figure 2. Vesperopterylus reconstructed using original drawings which were originally traced from the photo. Manual digit 4.4 is buried beneath other bones and reemerges to give its length. Pedal digit 1 turns laterally due to metacarpal arcing and taphonomic crushing. There is nothing reversed about it.

Lü et al were unable to segregate the skull bones.
Those are segregated by color here using DGS (Digital Graphic Segregation). See below. Some soft tissue is preserved on the wing. Note: I did not see the fossil first hand, yet I was able to discern the skull bones that evidently baffled those who had this specimen under a binocular microscope. Perhaps they were looking for the giant sclerotic rings in the anterior skull that are not present. Little ones, yes. Big ones, no.

Figure 1. Vesperopterylus skull with bones identified by DGS (digital graphic segregation). Lü et al. were not able to discern these bones and so left the area blank in their tracing. Note the complete lack of a giant eyeball in the front of the skull. Radius and ulna were removed for clarity and to show a complete lack of giant eyeballs (sclerotic rings) in the anterior skull. 

Figure 1. Versperopterylus skull with bones identified by DGS (digital graphic segregation). Lü et al. were not able to discern these bones and so left the area blank in their tracing. Note the complete lack of a giant eyeball in the front of the skull. Radius and ulna were removed for clarity and to show a complete lack of giant eyeballs (sclerotic rings) in the anterior skull.

This skull reconstruction
(Fig. 4) is typical of every other anurognathid, because guesswork has been minimized here. After doing this several times with other anurognathids, I knew what to look for and found it. No giant sclerotic rings were seen in this specimen.

Figure 4. Vesperopterylus skull reconstructed from color data traced in figure 3.

Figure 4. Versperopterylus skull reconstructed from color data traced in figure 3. Due to the angled sides of the skull some foreshortening was employed  to match those angles. Original sizes are also shown.

With regard to perching
all basal pterosaurs could perch on branches of a wide variety of diameters by flexing digit 1–4 while extending digit 5, acting like a universal wrench (Peters 2000, FIg. 5). This ability has been overlooked by other workers for the last two decades,

Figure 1. The pterosaur Dorygnathus perching on a branch. Above the pes of Dorygnathus demonstrating the use of pedal digit 5 as a universal wrench (left), extending while the other four toes flexed around a branch of any diameter and (right) flexing with the other four toes. As in birds, perching requires bipedal balancing because the medially directed fingers have nothing to grasp.

Figure 1. The pterosaur Dorygnathus perching on a branch. Above the pes of Dorygnathus demonstrating the use of pedal digit 5 as a universal wrench (left), extending while the other four toes flexed around a branch of any diameter and (right) flexing with the other four toes. As in birds, perching requires bipedal balancing because the medially directed fingers have nothing to grasp.

I have not yet added Versperopterylus
to the large pterosaur tree.

References
Lü J-C et al. 2017. Short note on a new anurognathid pterosaur with evidence of perching behaviour from Jianchang of Liaoning Province, China. From: Hone, D. W. E., Witton MP and Martill DM(eds) New Perspectives on Pterosaur Palaeobiology.
Geological Society, London, Special Publications, 455, https://doi.org/10.1144/SP455.16
Peters D 2000. Description and Interpretation of Interphalangeal Lines in Tetrapods. 
Ichnos, 7: 11-41

 

Sagittarius, Cariama and the ‘Terror birds’

Sagittarius is not only a constellation of the zodiac,
it’s a genus.

Figure 1. Phorusrhacos to scale with Dinornis, Struthio and Homo.

Figure 1. Phorusrhacos to scale with Dinornis, Struthio and Homo.

The giant Phorusrhachids or terror birds
were some of the largest predators of the Cenozoic. Essentially they were theropod dinosaurs retooled with hooked beaks and short tails. Not only do they have living relatives in the seriema, genus Caraima, they nest close to the base of some of the sweet songbirds and budgies we’ve all let sit on our fingers! Imagine the gene pool!!

Figure 2. Sagittarius (secretary bird) and Cariama (seriema). While clearly related, these two nest at the base of two different major bird clades.

Figure 2. Sagittarius (secretary bird) and Cariama (seriema). While clearly related, these two nest at the base of two different major bird clades.

Seriema
(genus Cariama cristatus, Linneaus 1766) is an extant long-legged snake and small prey predator of the high grasslands from Argentina. Despite their relatively short wings, Cariama is capable of flight, though rare and usually as last resort escape from predators.

Figure x. Cariama cristatus, the seriema in several views.

Figure x. Cariama cristatus, the seriema in several views.

Secretary bird
(genus: Sagittarius serpentarius) (Miller 1779is extant hook-beaked bird of prey that cruises tall grasses in search of small prey including snakes. The name likely comes from the Arabic, saqr-et-tair, or ‘hunter bird’. Standing 1m tall on extended legs, this otherwise eagle-like bird has relatively short wings.

Figure 1. The secretary bird, Sagittarius serpentaris and those extraordinary long legs.

Figure 1. The secretary bird, Sagittarius serpentaris and those extraordinary long legs and feet. About four feet tall.

In the large reptile tree (LRT, 1054 taxa) Sagittarius is a sister to Cariama and both are close to the terror birds. At present there are very few birds in the LRT.

Figure 2. Llallawavis skeleton, one of the most complete phorusrhacids known

Figure 2. Llallawavis skeleton, one of the most complete phorusrhacids known

Llallawavis scagliai (“ya-ya-WA-vis”; Degrange et al. 2015; Pliocene, 3.5 mya; 1.2m tall) is a member of the Phorushacidae or terror birds. Llallawavis is the most complete fossil yet found from this clade. Distinct from Sagittarius and Cariama, Llallawavis had a larger skull and vestigial wings.

Figure 3. Llallawavis skull in 3 views with DGS identifying bones, many of which are fused to one another. Image from DeGrange et al. with DGS added. Note DeGrange et al. labeled bones but did not delineate sutures. That needs to be done. Here the palatine is shown to be restricted to a small area below the maxilla and the rest is the pterygoid. Note the expansion of the maxilla in the reinforcement of this killing beak.

Figure 3. Llallawavis skull in 3 views with DGS identifying bones, many of which are fused to one another. Image from DeGrange et al. with DGS added. Note DeGrange et al. labeled bones but did not delineate sutures. That needs to be done. Here the palatine is shown to be restricted to a small area below the maxilla and the rest is the pterygoid. Note the expansion of the maxilla in the reinforcement of this killing beak.

Skull bones are fused
in many birds including Llallawavis. Even so, DGS is used to tease out former sutures to greater or lesser success. This is something that needs to be done by authors with firsthand access to original material. 

The pelvis of Llallawavis was longer, especially posterior to the acetabulum, and the legs not so long as in extant grassland birds (above). The posterior torso was deeper and pedal digit 3 was longer. 

Figure 4. Phorusrhacus skull in three views. The normally gracile bones of a bird skull are here reinforced on this giant predator that killed with its beak.

Figure 4. Phorusrhacus skull in three views. The normally gracile bones of a bird skull are here reinforced on this giant predator that killed with its beak.

Phorursrhacus longissimus 
(Ameghino, 1887; Miocene, 2.5m tall)

Hacket et al. 2008 report
both Cariama and Sagittarius nest at the base of adjoining clades. So they are relatively closely related themselves and likely developed short wings and long legs in parallel. I say this because all related taxa have shorter legs and larger wings.

Cariama nests at the base of falcons + parrots + Passeriformes (perching birds). Sagittarius nests at the base hawks and eagles, + owls + mouse birds + trogons + hornbills + woodpeckers + kingfishers and kin.

The overall pattern in both clades
is from vicious terrestrial and aerial predator to smaller seed-eating songbird on the one hand and smaller insect- and fish-eater on the other.

References
Alvarenga HMF and Hófling E 2003. Systematic revision of the Phorusrhacidae (Aves: Ralliformes) Papéis Avulsos de Zoologia 43(4):55-91.
Ameghino F 1887.
Enumeración sistemática de las espécies de mamíferos fósiles coleccionados por Carlos Ameghino en los terrenos Eocenos de la Patagonia austral y depositados en el Museo de La Plata. Boletim Museo La Plata, 1:1-26.
Degrange, FJ et al. 2015. A new Mesembriornithinae (Aves, Phorusrhacidae) provides new insights into the phylogeny and sensory capabilities of terror birds. Journal of Vertebrate Paleontology. 35 (2): e912656. doi:10.1080/02724634.2014.912656.
Hackett SJ et al. 2008. A Phylogenomic Study of Birds Reveals Their Evolutionary History. Science 320, 1763–1768.
Linneaus C 1766. Systema naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio duodecima, reformata. Holmiae. (Laurentii Salvii).: 1-532.
Statius Müller PL 1776. Des Ritters Carl von Linné Königlich Schwedischen Leibarztes &c. &c. vollständigen Natursystems Supplements- und Register-Band über alle sechs Theile oder Classen des Thierreichs. Mit einer ausführlichen Erklärung. Nebst drey Kupfertafeln.Nürnberg. (Rapse).

wiki/Secretarybird, Sagittarius
wiki/Llallawavis

What is the enigmatic Otter Sandstone (Middle Triassic) diapsid?

Coram, Radley and Benton 2017
presented a “small diapsid reptile [BRSUG 29950-12], possibly, pending systematic study, a basal lepidosaur or a protorosaurian.” According to Coram et al. “The Middle Triassic (Anisian) Otter Sandstone was laid down mostly by braided rivers in a desert environment.”

Figure 1. The Middle Triassic Otter Sandstone diapsid BRSUG 29950-12 under DGS nested with basalmost lepidosaurs like Megachirella.

Figure 1. The Middle Triassic Otter Sandstone diapsid BRSUG 29950-12 under DGS nested with basalmost lepidosaurs like Megachirella. Skeleton is exposed in ventral (palatal) view.

The LRT is here to nest and identify published enigmas
The large reptile tree (LRT 1041 taxa) nests BRSUG 29950-12 with the basalmost lepidosaur Megachirella. They are a close match and preserve nearly identical portions of their skeletons (Fig. 2). Megachirella was originally considered a sister to Marmoretta, another basal sphenodontian from the much later Middle/Late Jurassic.

FIgure 2. Megachirella (Renesto and Posenato 2003) is a sister to the BSRUG diapsid.

FIgure 2. Megachirella (Renesto and Posenato 2003), also from Middle Triassic desposits, is a sister to the BSRUG diapsid and provides a good guide for its eventual reconstruction.

At the base of the Lepidosauria
in the LRT nests Megachirella, derived from a sister to Sophineta (Early Triassic) and Saurosternon + Palaegama (Latest Permian) and kin. Sisters to Megachirella within the Lepidosauria include the tritosaurs Tijubina + Huehuecuetzpalli (Early Cretaceous), Macrocnemus (Middle Triassic) and the prosquamate Lacertulus (Late Permian). Also similar and related to Palaegama is Jesairosaurus (Middle Triassic). So the genesis of the Lepidosauria is Late Permian. The initial radiation produced taxa that continued into the Early Cretaceous. The radiation of derived taxa continued with three major clades, only one of which, the Tritosauria, is now completely extinct.

Note
It is important to remember that lepdiosaurs and protorosaurs are not closely related, but arrived at similar bauplans by convergence, according to the LRT. The former is a member of the new Lepidosauromorpha. The latter is a member of the new Archosauromorpha. Last common ancestor: Gephyrostegus and kin.

Nesting at the base of the Lepidosauria
in the Sphenodontia clade makes the BSRUG specimen an important taxon. Let’s see if and when this taxon is nested by academic workers that they include all of the pertinent taxa and confirm or re-discover the Tritosauria. The LRT provides a good list of nearly all of the pertinent taxa that should be included in that future study, many of which are listed above. Based on that list, the BSRUG specimen is a late-survivor of a perhaps Middle Permian radiation of basal lepidosaurs.

References
Coram RA, Radley JD and Benton MJ 2017. The Middle Triassic (Anisian) Otter Sandstone biota (Devon, UK): review, recent discoveries and ways ahead. Proceedings of the Geologists’ Association in press. http://dx.doi.org/10.1016/j.pgeola.2017.06.007

Pterodactylus manual digit 5

Tiny, vestigial manual digit 5
sits on the top of the giant axially rotated metacarpal 4 of all pterosaurs. Here (Fig. 1) manual digit 5 is curled up on this Pterodactylus scolopaciceps specimen (BSP 1937 I 18), a pregnant pterosaur. Photoshop helps this digit ‘pop’ making it harder to overlook. A reconstruction unrolls it.

Figure 1. Manual digit 5 on top of the giant metatarsal 4 on Pterodactylus. It's easy to overlook, until you look for it.

Figure 1. Manual digit 5 on top of the giant metatarsal 4 on Pterodactylus. It’s easy to overlook, until you look for it.

References
Broili F 1938. Beobachtungen an Pterodactylus. Sitz-Bayerischen Akademie der Wissenschaten, zu München, Mathematischen-naturalischenAbteilung: 139–154.
Wellnhofer P 1970. Die Pterodactyloidea (Pterosauria) der Oberjura-Plattenkalke Süddeutschlands. Abhandlungen der Bayerischen Akademie der Wissenschaften, N.F., Munich 141: 1-133.

wiki/Pterodactylus