Mid-Cretaceous lizards in amber from Myanmar

A new paper
from Daza et al. (2016) brings us several lizards in amber from the Mid Cretaceous (Fig. 1).

Figure 1. Mid-Cretaceous lizards in amber from Daza et al. 2016. Highlighted specimens are examined here.

Figure 1. Mid-Cretaceous lizards in amber from Daza et al. 2016. Highlighted specimens are examined here.

I was chiefly interested in
the unidentified ones, JZC Bu267 (Fig. 2) and JZC Bu1803 (Fig. 4).

Figure 2. JZC Bu 267 nests with the pre-snake, Jucarseps in the large reptile tree.

Figure 2. JZC Bu 267 nests with the pre-snake, Jucarseps in the large reptile tree.

JZC Bu 267
is a tiny, slender, short-legged, long-toed lizard that nests with the Early Cretaceous pre-snake, Jucarseps, (Bolet and Evans 2012, Fig. 3) in the large reptile tree. This nesting is based on relatively few traits as the skull is largely missing while dermis covers large portions of the post-crania. The two are about the same size and overall proportions.

The authors report, “The preservation of  JZC Bu267 is exceptional; it includes the epidermis and soft tissues and even a unique extended tongue tip with a narrow medial projection that does not resemble the form of any described squamate tongues.” According to Wikipedia, reptiles developed forked tongues in several clades independently.

Figure 1. Jucaraseps in situ. This tiny long lizard is in the lineage of terrestrial snakes.

Figure 3. Jucaraseps in situ. This tiny long lizard is in the lineage of terrestrial snakes and nests as a sister to JZC Bu 267,

So this find
extends the range of the Jucarseps clade from SW Europe to SE Asia.

Figure 4 JZC-Bu1803 has a relatively large skull. This and other traits nest it with the basal scleroglossan, Calanguban in the large reptile tree.

Figure 4 JZC-Bu1803 has a relatively large skull. This and other traits nest it with the basal scleroglossan, Calanguban in the large reptile tree.

JZC Bu1803
(3.2cm snout vent length) Is more thoroughly covered in fine scales. Nevertheless, a large enough list of traits was gleaned from the photo to nest JZC Bu 1803 with the basal scleroglossan, Calanguban (Simoes, Caldwell and Kellner 2014, Early Cretaceous), which is also the same size.

According to Daza et al. “The ventral scales are large, quadrangular, and arranged in regular transverse and longitudinal rows as in most living teiids and lacertids. Remarkable features of this specimen are the extremely long digits and claws.

“A digital endocast of the leftmaxilla exposed the entire tooth row section, a dentition including about 14 functional teeth, and an estimated 19 tooth loci. Tooth attachment is pleurodont and morphology is heterodont, with an abrupt transition from conical and recurved teeth (first 12) to tricuspid (with divided crowns, last 7). Tricuspid (or triconodonot) dentition is widespread among squamates. Among extant groups, the combination of anterior fang-like and posterior tricuspid teeth with parallel margins, where mesial and distal cusps are shorter than the main apex,most closely resembles that of lacertids and teiids.”

Figure 4. Calanguban nests as a sister to JZC Bu 1803 in the large reptile tree.

Figure 5. Calanguban nests as a sister to JZC Bu 1803 in the large reptile tree.

So this find
extends the range of the Calanguban clade from SW Europe across the then narrow Atlantic to NE Brazil.

Figure 6. The two new and unidentified amber embedded specimens nest as squamates that already have names here.

Figure 6. The two new and unidentified amber embedded specimens nest as squamates that already have names here.

The authors indicate
that more data will be forthcoming on these specimens. More can be seen on YouTube here.

References
Bolet A and Evans SE 2012. A tiny lizard (Lepidosauria, Squamata) from the lower Cretaceous of Spain. Palaeontology 55:491-500.
Daza J, Sanley EL, Wagner P, Bauer A and Grimaldi DA 2016. Mid-Cretaceous amber fossils illuminate the past diversity of tropical lizards. Science Advances 2(3): e1501080. DOI: 10.1126/sciadv.1501080
Simoes TR, Caldwell MW and Kellner AWA 2014.
 A new Early Cretaceous lizard species from Brazil, and the phylogenetic postion of the oldest known South American squamates. Journal of Systematic Palaeontology. http://dx.doi.org/10.1080/14772019.2014.947342

YouTube with rotating scans

 

 

 

 

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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.

 

The other Slavoia and the holotype

Earlier we looked at the basal amphisbaenid, Slavoia darevskii (Fig. 3 below, Talanda 2015).

I just read about the holotype (Sulminski 1984) and at least 45 other specimens attributed to Slavoia, like this one (Fig. 1, ZPAL MgR-III/77, Campanian, Late Cretaceous). Six of the 46 skulls are associated with postcranial skeletons, like the holotype, Fig. 2, ZPAL MgR-I/8). If you think this skull looks like Macrocephalosaurus, you’re not the only one.

Slavoia specimen ZPAL MgR III/77 nests not with amphisbaenids, but with Macrocephalosaurus, a contemporary from the same horizon.

Slavoia specimen ZPAL MgR III/77, one of 46 skulls,  nests not with amphisbaenids, but with Macrocephalosaurus, a contemporary from the same horizon. Talanda reports, “The specimen has only half of the elements visible in this drawing. The skull roof and the middle part are not preserved.”

Sulminski nested Slavoia with scincomorphan lizards, but he reported, “It is interesting that described here lizard displays some characters similar to macrocephalosaurid and polyglyphanodontid  species discovered in the same localities of Mongolia. This concerns also particularly the structure of the temporal region, palatal construction and in number of teeth.”

The #77 and #8 specimens nested with macrocephalosaurs in the large reptile tree.

On the other hand,
the #112 specimen nested at the base of the amphisbaenids, as we learned earlier. So the #112 specimen needs a new generic name, or there are other issues that need be dealt with.

Dragging
the amphisbaenid #112 specimen over to the macrocephalosaur specimens adds 17 steps to the most parsimonious tree score. That’s a very low number considering that there are only 17 taxa separating the macrocephalosaurs from the amphisbaenids in the large reptile tree. So, there is a bit of convergence going on here between the macrocephalosaurids and amphisbaenids. The authors note all the skulls vary in size and shape, which they attribute to ontogeny and intraspecific variation. And, of course, none are perfectly preserved. Talanda reports, “The [#77] specimen has only a half of the elements visible in this drawing. The skull roof and the middle part are not preserved.”

Figure 2. The holotype of Slavoia (#8) compared to the lateral view skull (#77). While larger, the #77 skull is relatively shorter. These two nest together in the large reptile tree along with macrocephalosaurids.

Figure 2. The holotype of Slavoia (#8) compared to the lateral view skull (#77). While larger, the #77 skull is relatively shorter. These two nest together in the large reptile tree along with macrocephalosaurids. Note the large size of the limbs.

Does this represent a solution?
Sulimski (1984) recognized the similarity between his skinks and macrocephalosaurids. Talanda (2015) considered his specimen a basal amphisbaenid, a clade derived from skinks in the large reptile tree, but Talanda nested his amphisbaenids between Cryptolacerta and Dibamus + snakes. So there is disagreement here.

Figure 1. basal amphisbaenid Slavoia from Talanda 2015, showing in situ fossil, tracing by Talanda and colorizing added here. Several bones, like the lacrimal and prefrontal, are missing in the Talanda tracing, which evidently was not traced from this photograph.

Figure 3. The #112 specimen from Talanda 2015 which both he and I nested as a basal amphisbaenid. Note the similarity to macrocephalosaurids (above). The teeth appear to be more robust here, as they are in the palate view specimens that have more of an amphisbaenid palate. I don’t see large limbs here, but limb size varies in the amphisbaenids.

Phylogeny is sometimes simple and straightforward.
Sometimes it is not.

This case shows the importance
of using specimen-based taxa in analyses, not specific, generic or suprageneric taxa. It would not be okay to take the best traits from several Slavoia specimens because some may not be Slavoia specimens! This case also highlights a need to determine where every one of these varied Slavoia specimens do nest. And it will be okay if some are lumped while others are split.

The limbs are large in the #8 specimen, but are not visible in the #112 specimen. In amphisbaenids limbs, even in basal taxa, can be vestiges, but not vestiges in the very derived Bipes.

We all have a lot to learn here. It’s not all set in stone.

References
Sulimski A 1984. A new Cretaceous scincomorph lizard from Mongolia. Palaeontologia Polonica, 46, 143–155.
Talanda M 2015.
 Cretaceous roots of the amphisbaenian lizards. Zoologica Scripta. doi:10.1111/zsc.12138

Reconstruction from jumbled scraps: the squamate, Kuroyuriella

Figure 1. The skull of Kuroyuriella reconstructed from bone scraps (above), most of which are layered on top of one another. Not all elements are identified, but enough are to nest this taxon with Ophisaurus.

Figure 1. The skull of Kuroyuriella (represented by two specimens of different size) reconstructed from bone scraps (above), most of which are layered on top of one another. Not all elements are identified, but enough are known to score and nest this taxon with Ophisaurus.

When provided disarticulated scraps,
start with the easy bones, then fill in the gaps in the puzzle. Sometimes, as in Kuroyuriella mikikoi (Evans and Matsumoto 2015, Early Cretaceous), there are enough parts to more or less recreate the skull most similar (among tested taxa in the large reptile tree) to that of Ophisaurus and basal to Myrmecodaptria and CryptolacertaEvans and Matsumoto nested Kuroyuriella  between Huehuecuetzpalli and the suprageneric clade Rhynchocephalia, both well outside the Squamata.

From the online paper:
“Together, SBEI 1510 and SBEI 1608, as type and referred specimen, characterize Kuroyuriella mikikoi as a small lizard having paired frontals with deep subolfactory processes; a median parietal without a parietal foramen, with sculpture of low relief, and with lateral shelves that restricted the adductor muscle origins to the ventral surface; upper temporal fenestrae that were at least partially closed by expanded postorbitofrontals; an unsculptured maxilla with a strongly concave narial margin; a large flared prefrontal; and a slender, relatively small pterygoid. In the shallow lower jaw, the teeth are closely packed, cylindrical, and pleurodont with lingual replacement; a subdental ridge is present; the dentary bears a tapering coronoid process that braces the coronoid, and has a posterior extension with a curved free margin; the surangular, angular, and splenial are all present and the surangular is shallow; the adductor fossa is open but not expanded; and the articular surface is asymmetrical.

In order to explore the affinities of Kuroyuriella mikikoi, it was coded into the matrix of Gauthier et al. (2012), as extended by Longrich et al. (2012) (184 characters coded out of 622, 70.4% missing data),

The consistent placement of Kuroyuriella on the squamate stem is problematic and probably artifactual, but whether the weighted analysis is giving a more accurate placement is uncertain. Of the derived character states possessed by Kuroyuriella, 76 [1] (postorbital partly occludes upper temporal fenestra), 364 [1] (dentary coronoid process extends beyond level of coronoid apex), 367 [2] (coronoid process of dentary overlaps most of anterolateral surface of coronoid), and 369 [2] (dentary terminates well posterior to coronoid apex) provide some support for placement of Kuroyuriella on the stem of scincids, and 129 [1] (prefrontal extends to mid-orbit), 104 [1] (absence of parietal foramen) and 385 [1] (posterior mylohyoid foramen posterior to coronoid apex) would be consistent with that placement. However, given the considerable difference between the results using equal weighting and Implied Weighting, Kuroyuriella remains incertae sedis pending recovery of more complete material.”

Figure 2. Ophisaurus, the extant glass snake or legless lizard is close to Kuroyuriella in the large reptile tree.

Figure 2. Ophisaurus, the extant glass snake or legless lizard is close to Kuroyuriella in the large reptile tree.

Here
Ophisaurus (Fig. 2) and Kuroyuriella both nest will within the Squamata, not ouside. of it in the large reptile tree. Reconstruction of the skull helps to ‘see’ this lizard as it was. I can’t imagine how difficult it would be to do try to establish traits  with a jumble of disarticulated bones.

As you’ll see, I think the parietal foramen was present. The parietal may have had longer posterior processes, now broken off.

References
Evans SE and Matsumoto R 2015. An assemblage of lizards from the Early Cretaceous of Japan. Palaeontologia Electronica 18.2.36A: 1-36
palaeo-electronica.org/content/2015/1271-japanese-fossil-lizards
http://palaeo-electronica.org/content/2015/1271-japanese-fossil-lizards

Urumqia – a very basal lepidosauromorph

Urumqia liudaowanensis (Zhang et al. 1984) ~20 cm snout-vent length, Lower Permian.

Figure 1. Urumqia liudaowanensis (Zhang et al. 1984) ~20 cm snout-vent length, Late Permian.

Here’s a gephyrostegid/basal amniote/basal lepidosauromorph
you may not have heard of. (Remember lepidosauromorphs in the large reptile tree constitute about half of all amniotes). It is considered China’s oldest known tetrapod.

Urumqia liudaowanensis (Zhang et al. 1984, Fig. 1) ~20 cm snout-vent length, Late Permian Lucaogou Formation), was originally considered a discosaurid seymouriamorph. Here it nests at the base of the lepidosauromorph reptiles. Shifting Urumqia to the discosaurid seymouriamorphs adds 39 steps to the large reptile tree.

Derived from 
Gephyostegus bohemicusUrumqia was basal to Bruketererpeton, Thuringothyris, and all lepdiosaurs, turtles, diadectids, pterosaurs and other various lepidosauromorphs starting with Saurorictus and Cephalerpeton. Phylogenetically Urumqia must have made a first appearance in the Viséan (335 mya, Mississipian, Carboniferous) despite its late appearance in the Late Permian (255 mya).

Figure 1. Basal amniotes to scale. Click to enlarge.

Figure 2. Basal amniotes to scale. Click to enlarge. Urumqia nests on the right hand column with Cephalerpeton and Thuringothyris.

Distinct from G. bohemicus,
Urumqia had shorter limbs, longer (but not long) posterior dorsal ribs and a robust tail with elongate caudals. The palate included a suborbital fenestra. The cheek may have included a small lateral temporal fenestra convergent with others. The carpals and tarsals were poorly ossified.

Figure 4. Extant lizards, A. gravid, B. in the process of laying eggs, C. with egg clutch.

Figure 3. Extant lizards, A. gravid, B. in the process of laying eggs, C. with egg clutch.

Notably
the posterior dorsal ribs were much shorter than the gastralia. So the gastralia create a wide posterior torso, ideal for carrying large amniote eggs (Fig. 3), as we learned earlier.

The new topology of basal reptiles
is based on the inclusion of several more species based taxa not previously considered. This new topology show that synapsids were not the first clade to branch off. Rather all taxa closer to archosaurs (here considered the new Archosauromorpha) split from all taxa closer to lepidosaurs (here considered the new Lepidosauromorpha) at the onset of the Reptilia (=Amniota).

References
Zhang F, Li Y, and Wan X. 1984. A new occurrence of Permian seymouriamorphs in Xinjiang, China. Vertebrate Palasiatica22(4):294-306.

Sirenoscincus mobydick: the only terrestrial tetrapod with ‘flippers’

Sakata and Hikida 2003
introduced us to a new and extant fossorial (burrowing) lizard (Sirenoscincus yamagishii. Fig.1). The authors described having “an elongated body and eyes covered by scales, lacking external ear openings and pigmentation through- out the body, resembles Cryptoscincus and Voeltzkowia. However it differs from these or any other scincid genera known to the present in having small but distinct forelimbs, each with four stout claws, and complete lack of hind limbs.”

Figure 1. Sirenoscincus-yamagishii, a new skink with forelimbs and no hind limbs. Note the four fingers.

Figure 1. Sirenoscincus-yamagishii, a new skink with forelimbs and no hind limbs. Note the four fingers.

Sirenoscincus is a very tiny lizard
with 53 presacral vertebrae and a tail longer than the snout vent length. The snout is pointed and the lower jaw is countersunk, like a shark’s mouth. The forelimbs are tiny with indistinct fingers and four stout claws. An outgroup taxon, Gymnophthalmus, also has tiny fingers and the medial one is a vestige.

Then a second Sirenoscincus species was discovered
S. mobydick (Miralles et al. 2012, Fig. 2; see online interview here). “The specicific epithet refers to Moby Dick, the famous albino sperm whale imagined by Herman Melville (1851), with whom the new species shares several uncommon characteristics, such as the lack of hind limbs, the presence of fipper-like forelimbs, highly reduced eyes, and the complete absence of pigmentation.”

Figure 3. Sirenoscincus mobydick.

Figure 2. Sirenoscincus mobydick.

S. mobydick has only five scleral ring bones, the lowest of any lizard. The authors reinterpreted several scale patterns on the holotype species. So, mistakes do happen, even at a professional level. Those mistakes get corrected and no one gets upset (hopefully unlike the blogosphere!).

Figure 2. Sireonscincus mobydick, named for its flippers, unique for any terrestrial tetrapod.

Figure 3. Sireonscincus mobydick, named for its flippers, unique for any terrestrial tetrapod. Colors added.

Fossorial skinks are often described by their scale patterns.
Unfortunately that doesn’t work with prehistoric skeletons, so I was only able to add only the bone traits of Sirenoscincus mobydick to the large reptile tree (subset shown in Fig. 7). The skeletal traits nested S. mobydick between two skinks Gymnophthalmus and Sineoamphisbaena, another taxon with forelimbs only (granted, the posterior half is not known). Like Sineoamphisbaena, Sirenoscincus prefrontals contact the postfrontals, unlike those of most lizards. In derived taxa the quadrate leans almost horizontally. That’s not the case with Sirenoscincus, which has a vertical but bent quadrate.

Figure 4. Sirenoscincus mobydick pectoral and pelvic girdles. Colors added.

Figure 4. Sirenoscincus mobydick pectoral and pelvic girdles. Colors (other then the original red) are added here.

Miralles et al. (2012) reported,  “Due to the absence of molecular data the phylogenetic position of the genus Sirenoscincus is still an enigma, even if we can reasonably claim it belongs to the Malagasy scincine clade.” In the last few days author, A. Miralles reported via email that molecular data have recently nested S. mobydick with skinks. 

Figure x. Chalcides guentheri and C. occellatus, two skinks were morphology quite similar to that of Sirenoscincus.

Figure 5. Chalcides guentheri and C. occellatus, two skinks with morphologies quite similar to that of Sirenoscincus. C. oscellatus has longer legs. Note the wrapping of the maxilla over the premaxilla which is continued in Sirenoscincus mobydick which has a smaller orbit. Also note the prefrontal and postfrontal are closer to contact in C. ocellatus.

An outgroup taxon is Chalcides (Fig. 5) where you’ll note the same long overlap of the maxilla over the premaxilla. A sister, Sineoamphisbaena also has an underslung mandible, but much more robust forelimbs (only the humerus is known). Could this be a redevelopment? Or has the cladogram missed something, needing more taxa perhaps, to fill this gap? No doubt new taxa will fill these various morphological gaps.

Figure 6. Sineoamphisbaena is a sister to Sirenoscincus in which the prefrontal contacts the postfrontal.

Figure 6. Sineoamphisbaena is a sister to Sirenoscincus in which the prefrontal contacts the postfrontal. The lower jaw is countersunk and the upper teeth don’t point down, they point in (medially).

New data has revised the relationship of skinks to reptiles in the large reptile tree (Fig. 7). Some to most of the confusion (here or earlier) likely results from the massive convergence in burrowing lizards. And some portion is also due to having good data (old line drawings) replaced by better data (rotating online images), often thanks to the good scientists over at Digimorph.org.

Figure 7. Here's where Sirenoscincus nests in the lizard family tree.

Figure 7. Here’s where Sirenoscincus nests in the lizard family tree.

References
Miralles A et al. 2012. Variations on a bauplan: description of a new Malagasy “mermaid skink” with flipper-like forelimbs only (Scincidae, Sirenoscincus Sakata & Hikida, 2003). Zoosystema 34(4):701-719.
Sakata S and Hikida T 2003. A fossorial lizard with forelimbs only: description of a new genus and species of Malagasy skink (Reptilia: Squamata: Scincidae). Current Herpetology 22:9-15.

Have you ever seen an Anolis quite like this?

This is a striking variation on the Anolis lizard theme with an extended premaxilla/snout. Meet Anolis proboscis, aka the Pinocchio lizard. This trait is restricted to males and this species was thought to be extinct for several decades. Click here or on the image to learn more.

Figure 1. Long-nosed Anolis from the Luke Mahler lab.

Figure 1. Long-nosed Anolis from the Luke Mahler lab. Only males have this trait.  Click to learn more.

The image comes from the Luke Mahler website. Dr. Mahler is a former student of Jonathan Losos, now at Harvard, formerly of Washington University, here in St. Louis. Jonathan’s work with Anolis has shed new light on the process of evolution.

References
Poe et al. 2012.
Morphology, Phylogeny, and Behavior of Anolis proboscis. Breviora Number 530 :1-11. 2012 online here and here.