My what big eyes you have, Lyriocephalus!

Looking like some sort of medieval fever dream,
meet Lyriocephalus, the hump-nosed lizard (Fig. 1), a cousin to Draco, the gliding lizard. Distinct from Draco, the body of this insectivore is laterally compressed, not laterally extended.

Figure 1. Lyriocephalus in vivo.

Figure 1. Lyriocephalus in vivo.

Probably the largest eyes
relative to the skull of any tetrapod. Lyriocephalus, is an arboreal jungle lizard with an anterodorsal naris and a small antorbital fenestra. Note the arching postorbital contacting the prefrontal.

Figure 2. Lyriocephalus skull in several views. Note the arching of the postorbital to contact the prefrontal.

Figure 2. Lyriocephalus skull in several views. Note the arching of the postorbital to contact the prefrontal. And did I mention that antorbital fenestra?

Lyriocephalus scutatus (Merrem 1820) is represented by a skeleton at Morphospace.org where you can rotate the skeleton on your monitor. Note the brevity of the tail of this agamid iguanid, There are more in vivo pix here. And a video here.

Figure 3. Lyriocephalus skeleton from Morphobank.org, where you can rotate digitized skeletons.

Figure 3. Lyriocephalus skeleton from Morphobank.org, where you can rotate digitized skeletons.

References
Merrem B 1820. Versuch cines Systems Amphihien Tentamen Systcmatis Amphibiorum. Marburg, Krieger.

wiki/Draco
wiki/Lyriocephalus

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Saichangurvel: not an iguanid, but very close…

This appears to be yet another case of a priori taxon exclusion.
Saichangurvel davidsoni (Conrad and Norell 2007; (IGM 3/858; Late Cretaceous) was originally considered a member of the Iguania, but here nests with Acanthodactylus, a lacertid taxon not mentioned in the original text, but nesting as a sister to the Iguania and is a basalmost scleroglossan.

Conrad and Norell report
“Iguania, like Squamata as a whole, has a rich, but patchy fossil record. Although many Cretaceous species have been identified, Saichangurvel davidsoni is the first known from a complete skeleton. Indeed, the recent revelation that none of the Euposaurus remains may be diagnosed as iguanians (Evans, 1993) renders Saichangurvel davidsoni the earliest iguanian known from complete remains.”

Contra Evans 1993
The LRT nests tiny Euposaurus with the much larger Iguana (Fig. 2) as yet one more example of phylogenetic miniaturization at the genesis of major clades. In this case the major clades are Iguania and Squamata. BTW the ResearchGate.net link for Euposaurus takes you to another SE Evans paper.

Distinct from Acanthodactylus,
the teeth of Saichangurvel have three cusps, convergent with Iguana and that may be why the specimen was originally nested with iguanids. The upper temporal fenestrae are not reduced by a posterior extension of the postfrontal. Acanthodactylus has simple cone-shaped teeth.

Figure 1. Saichangurvel in situ, a complete squamate originally considered a member of Iguania but here nesting with Acanthodactylus.

Figure 1. Saichangurvel in situ, a complete squamate originally considered a member of Iguania but here nesting with Acanthodactylus.

The large reptile tree
(LRT) nests Saichangurvel very close to the Iguania (Fig. 2 in pink), but not in that clade. Unfortunately two of the top lizard experts in the world, Conrad and Norell, excluded taxa pertinent to the analysis, like Acanthodactylus and other basal scleroglossans (Fig 2 in green), That’s my only trump card here.

Figure 2. Subset of the LRT focusing on the Iguania and basal Scleroglossa, including Acanthodactylus and Saichangurvel

Figure 2. Subset of the LRT focusing on the Iguania and basal Scleroglossa, including Acanthodactylus and Saichangurvel

References
Conrad JL and Norell MA 2007. A complete late Cretaceous Iguanian (Squamata, Reptilia) from the Gobi and Identification of a new iguanian clade. American Novitates 3584:1-47.
Daza JD, Abdala V, Arias JS, Garcia-Lopez D and Ortiz P 2012. Cladistic Analysis of Iguania and a Fossil Lizard from the Late Pliocene of Northwestern Argentina”. Journal of Herpetology. 46(1):104-119.
Evans SE 1993. A re-evaluation of the Late Jurassic (Kimmeridgian) reptile Euposaurus (Reptilia: Lepidosauria) from Cerin, France. Geobios 27: 621–631.

The water-walker, the rib-glider and the frill-neck are all cousins!

Update March 5, 2016 with the addition of the cladogram from the large reptile tree.

Some reptile oddballs
>do< nest together. In this case, the extant “Jesus” lizard, Basiliscus, the rib-glider, Draco, and the frill-neck, Chlamydosaurus now nest together in the large reptile tree.

Figure 1. Draco volans. Note the anterior maxillary fangs, and the antorbital fenestra between the lacrimal and prefrontal, traits shared with Chlamydosaurus (Fig 2).

Figure 1. Draco volans. Note the anterior maxillary fangs, and the antorbital fenestra between the lacrimal and prefrontal, traits shared with Chlamydosaurus (Fig 2).

Draco (Fig. 1) and Chlamydosaurus (Fig. 2) are particularly interesting
as both share anterior maxillary fangs and an antorbital fenestra between the prefrontal and jugal (rather than between the lacrimal and maxilla as in other taxa with an antorbital fenestra). A long list of shared character traits unites these two still quite different lizards.

Figure 2. Chlamydosaurus also has anterior maxillary fangs and an antorbital fenestra between the prefrontal and lacrimal, as in Draco (Fig.1).

Figure 2. Chlamydosaurus also has anterior maxillary fangs and an antorbital fenestra between the prefrontal and lacrimal, as in Draco (Fig.1).

Basiliscus
is (at this point in the proceedings) a sister to the last common ancestor. But with that parietal crest, it has definitely evolved apart from the above two taxa for a long time.

Figure 3. Basiliscus, the "Jesus" lizard, does not share as many traits as Draco and Chlamydosaurus do, but is related, given the short list of Iguanids currently employed.

Figure 3. Basiliscus, the “Jesus” lizard, does not share as many traits as Draco and Chlamydosaurus do, but is related, given the short list of Iguanids currently employed.

We’ve seen this before, 
where and when some odd little reptiles shared more traits with each other than with any other tested reptiles. Members of the Fenestrasauria (Cosesaurus, Kyrgyzsaurus, Sharovipteryx, Longisquama, and pterosaurs) also include bipeds with dorsal frills. One of them also glided with outstretched ribs and legs, although distinct from Draco. In Sharovipteryx, the hind legs were much longer than the ribs.

Figure addendum 1. Cladogram of the Iguania, the sister taxa of the Scleroglossa, both members of the clade Squamata, a subset of the clade Protosquamata, the sister taxon to the Tritosauria.

Figure addendum 1. Cladogram of the Iguania, the sister taxa of the Scleroglossa, both members of the clade Squamata, a subset of the clade Protosquamata, the sister taxon to the Tritosauria. Many more scleroglossans are shown in the large reptile tree at ReptileEvolution.com.

We don’t have 
close prehistoric relatives for Draco or Chlamydosaurus yet. So at this point the evolution of rib-gliding or frill-spreading is not yet a gradual demonstration. But the other shared traits are, to my knowledge, unique synapomorphies.

I will update the cladogram this weekend.

 

Euposaurus: basal squamate/basal iguanid

Among the many lizards found in Late Jurassic  (155 mya) European lithographic limestones that have no living counterparts, there is one, Euposaurus (Fig. 1) that is basal to all members of the clade Iguania, which includes Iguana, the iguana; Phyronsoma, the horned lizard; Trioceros, the chameleon; and Draco, the rib-gliding lizard.

Euposaurus cirrensis, a basal squamate and basal  member of the clade Iguania.

Figure 1. Euposaurus cirrensis, (not the generic holotype) a basal squamate and basal member of the clade Iguania. The large orbit and less than fused ankles are primitive, not juvenile, traits.

Euposaurus cirinensis ( Lortet 1892, MHNL 15681, Late Jurassic, Kimmeridgian, 155 mya, 3.5cm snout vent length) nests as the basalmost member of the Iguania (Cocude-Michel 1963) and is a basal squamate. Evans (1994) assigned it to Squamata incerta sedis. The large skull and large orbit might seem to be juvenile traits, but all sister taxa share these traits. Liushusaurus and Calanguban are sister taxa at the base of the Scleroglossa.

Figure 2. Euposaurus insitu.

Figure 2. Euposaurus insitu.

Evans 1994 reexamined the three specimens attributed to Euposaurus and reported they “belong to different genera. Euposaurus thiolleri, the type species, is a juvenile pleurodont lepidosaur which is probably, but not certainly, a lizard. It has no characters which suggest that it is an iguanian and is here designated Lepidosauria incertae sedis. The remaining two specimens have an acrodont dentition and are juvenile rhynchocephalians. One is referable to Homoeosaurus; the other appears to belong to the group currently represented by Sapheosaurus, Kallimodon, Piocormus (aka Sapheosaurus) and Leptosaurus although the latter two may not be valid genera.”

Figure 2. Basal squamates. Here Euposaurus is a basal Iguania. Liushusaurus and Calanguban are basal Scleroglossa. Scandensia is presently their last common ancestor.

Figure 3. Basal squamates. Here Euposaurus is a basal Iguania. Liushusaurus and Calanguban are basal Scleroglossa. Scandensia is presently their last common ancestor.

Derived from ScandensiaEuposaurus is larger overall and has a larger skull with a robust palate. The tail is longer and more robust. The limbs are more robust. Scandensia is much smaller than its predecessor, the mis-named “Langobardisaurus” rossii, so the origin of lepidosaurs is one more case of miniaturization, as in mammals, birds and reptiles.

Figure 4. Langobardisaurus? rossii compared to tiny Scandensia.

Figure 4. Langobardisaurus? rossii compared to tiny Scandensia.

References
Cocude-Michel M 1963. Les rhynchocephaJes et les sauriens de calcaires
lithographiques (Jurassique supérieur) d’Europe occidentale. Nouvelles Archives
du Muséum d’Histoire Naturelle de Lyon 7: 1-187.
Evans SE 1994. A re-evaluation of the Late Jurassic (Kimmeridgian) reptile Euposaurus (Reptilia: Lepidosauria) from Cerin, France. Geobios 27(5):621-631.
Lortet M 1892. Les reptiles fossiles du Bassin du Rhone. Archives du Musee de
Histoire Naturelle, Lyon 5: 1-139.

image from planet-terre

Euposaurus corninesss 

Musée des confluences, Lyon / Pierre Thomas 

http://planet-terre.ens-lyon.fr/planetterre/objets/Images/Img307/307-rhynchocephales-Cerin-06.jpg