Quail hip joints are not good models for pterosaur hip joints

Manafzadeh and Padian 2018 tell us:
“Studies of soft tissue effects on joint mobility in extant animals can help to constrain hypotheses about joint mobility in extinct animals. However, joint mobility must be considered in three dimensions simultaneously, and applications of mobility data to extinct taxa require both a phylogenetically informed reconstruction of articular morphology and justifications for why specific structures’ effects on mobility are inferred to be similar. We manipulated cadaveric hip joints of common quail and recorded biplanar fluoroscopic videos to measure a ‘ligamentous’ range of motion (ROM), which was then compared to an ‘osteological’ ROM on a ROM map. Nearly 95% of the joint poses predicted to be possible at the hip based on osteological manipulation were rendered impossible by ligamentous constraints. Because the hip joint capsule reliably includes a ventral ligamentous thickening in extant diapsids,the hip abduction of extinct ornithodirans with an offset femoral head and thin articular cartilage was probably similarly constrained by ligaments as that of birds. Consequently, in the absence of extraordinary evidence to the contrary, our analysis casts doubt on the ‘batlike’ hip pose traditionally inferred for pterosaurs and basal maniraptorans, and underscores that reconstructions of joint mobility based on manipulations of bones alone can be misleading.”

Figure 6. Images of floating lizards. The small ones, like small pterosaurs, take advantage of surface tension to ride high while spread-eagle on the surface.

Figure 1a. Images of floating lizards. The small ones, like small pterosaurs, take advantage of surface tension to ride high while spread-eagle on the surface.

Manafzadeh and Padian 2018 are not phylogenetically informed.
They should have used lizards. Pterosaurs are not related to birds. Birds are archosaurs. Pterosaurs are lepidosaurs, which universally (except for legless taxa) assume a bat-like pose in their hind limbs when resting (Figs. 1, 2). Many articulated pterosaur fossils are found in the sprawling posture (Fig. 2) typically used for flying…but Manafzadeh and Padian are talking about quail hips and inferring similarity. That is the basic error here.

The clade ‘Ornithodira’
(= pterosaurs + dinosaurs, their last common ancestor and all descendants, Gauthier 1986) is a junior synonym for ‘Amniota’, which is a junior synonym for ‘Reptilia’ when more taxa are added to phylogenetic analysis, as demonstrated here: http://www.ReptileEvolution.com/reptile-tree.htm. This growing online study currently tests 1220 specimen-based taxa throughout the Tetrapoda. So here, as nowhere else, pterosaurs have the opportunity to nest with over 1200 candidate sisters.

Pterosaur outgroups
Macrocnemus, Tanystrospheus, Tanytrachleos, Langobardisaurus, Cosesaurus and Sharovipteryx are pterosaur outgroup taxa (Peters 2000, 2007) with an oblique femoral head and sprawling femora. In Peters (2000) pterosaurs and their outgroups were considered prolacertiforms, but with additional taxa (Peters 2007 and ReptileEvolution.com) taxa listed above join the lepidosaurs Huehuecuetzpalli and Tijubina in a new clade (Tritosauria) nesting between Rhynchocephalia (= Sphenodontia) and Squamata.

Pterosaur femur samples. A

Figure 1b. Pterosaur femur samples. Above, Pteranodon. Below, Anhanguera. Note the oblique angle of the femoral head. When the axes of the femoral neck and laterally-oriented acetabulum lined up a sprawling configuration was produced.

In pterosaurs the angle of the femoral shaft
in relation to the acetabular bowl is determined by the femoral neck, which is nearly at right angles to the shaft in the clade represented by Dimorphodon and Anurognathus. Padian famously compared erect Dimorphodon to erect birds (Padian 1987) and heartily endorsed the Ornithidira hypothesis without testing other pterosaur ancestor candidates among the Lepidosauria, some of which were not published until after 1987. In many other pterosaurs, like Anhanguera, Pteranodon and Quetzalcoatlus, the shaft and head of the femora are much more oblique (Fig. 1b), at times approaching collinear (Fig. 2). No pterosaur femora are presented in Manafzadeh and Padian 2018, only a quail pelvis and femur.

The Vienna Pterodactylus.

Figure 2. The Vienna Pterodactylus. Click to animate. Wing membranes in situ (when folded) then animated to extend them. The femora are sprawling because this is a lepidosaur, not an archosaur.


Young scientists:
Examples like Manafzadeh and Padian 2018 should inform you that even though some highly regarded paleontologists have made great discoveries and have stood up against Creationists, even they can put on blinders when it comes to direct attacks on cherished hypotheses. Neither Padian nor his students, nor any other professor nor their students, have ever, or will ever find pterosaur sister taxa among the Archosauriformes, no matter how much they believe that someday, somehow what they pray for and have faith in will happen. It’s been 18 years since the Ornithodira was struck down (Peters 2000) and pterosaurs were shown to nest outside the Archosauriformes. Padian and others simple ignore this trifle, hoping it will someday go away. And it will, unless others offer to take up the cause. Unfortunately, that’s the state of paleontology in 2018.

Everywhere, but here
testing the discoveries of others appears to be on the wane (see video below the references)… but that’s life. Question authority. Test evidence for yourself.

Gauthier JA 1986. Saurischian monophyly and the origin of birds. The Origin of Birds and the Evolution of Flight, K. Padian (ed.), Memoirs of the California Academy of Sciences 8:1–55.
Manafzadeh AR and Padian K 2018. ROM mapping of ligamentous constraints on avian hip mobility: implications for extinct ornithodirans. Proceedings of the Royal Society B Biological Sciences. Published 23 May 2018.DOI: 10.1098/rspb.2018.0727
Padian K 1983. Osteology and functional morphology of Dimorphodon macronyx (Buckland) (Pterosauria: Rhamphorhynchoidea) based on new material in the Yale Peabody Museum, Postilla, 189: 1-44.
Peters D 2000. A redescription of four prolacertiform genera and implications for pterosaur phylogenesis. Rivista Italiana di Paleontologia e Stratigrafia 106: 293-336.
Peters D 2007. The origin and radiation of the Pterosauria. Flugsaurier. The Wellnhofer Pterosaur Meeting, Munich 27

John Oliver thinks the following science problem is not funny.
Academic publications are unlikely to publish studies that simply confirm earlier discoveries. And yet… science depends on confirmation and ultimately consensus.

(Click to play video). After the first few minutes the video becomes less relevant):

As Oliver puts it:
There’s no Nobel Prize for fact checking.” Perhaps that is why few other workers are even considering taxa listed in the large reptile tree and large pterosaur tree that were shown to be relevant for more focused studies. And those that do (e.g. Baron and Barrett 2017 in their Chilesaurus study) are being notably taciturn about grabbing headlines for discoveries posted and time-stamped years earlier.

Quotes from this Oliver video:
“So you have all these exploratory studies that are taken as fact, that have never actually been confirmed.” 

“Replication studies are rarely funded. No one wants to do them.”

“Too often, a small study with nuanced tentative findings gets blown out of all proportion when it is presented to us, the lay public.”



2 thoughts on “Quail hip joints are not good models for pterosaur hip joints

  1. Seems to be the paradigm for paleontology: we need to compare fossils with modern animals, so use only samples far away in basic body plan and infer what we can from that. I see it too many times; dinosaurs have birdy hind legs, no calcaneal tubors, but many restorations use mammal leg musculature as inspiration. Sorry, folks, VERY unlikely.

    So here we have the fully bipedal, erect legged quail as a substitute for pterosaur legs. Makes sense only when one refuses to look at the evidence. So, it makes sense by paleolackological thinking. I agree with you on this one too, David. Keep up the good work!

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