Polyglyphanodontia, also known as the Borioteiioidea, is an extinct
clade
A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...
of
lizard
Lizards are a widespread group of squamate reptiles, with over 7,000 species, ranging across all continents except Antarctica, as well as most oceanic island chains. The group is paraphyletic since it excludes the snakes and Amphisbaenia alt ...
s from the
Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...
that includes around a dozen genera. Polyglyphanodontians were the dominant group of lizards in North America and Asia during the
Late Cretaceous
The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ...
. Most polyglyphanodontians are Late Cretaceous in age, though the oldest one, ''
Kuwajimalla kagaensis'', is known from the
Early Cretaceous
The Early Cretaceous ( geochronological name) or the Lower Cretaceous (chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145 Ma to 100.5 Ma.
Geology
Pro ...
(Valanginian to Hauterivian)
Kuwajima Formation
The Kuwajima Formation is an Early Cretaceous geologic formation in Japan. Its precise age is uncertain due to a lack of identifying fossils, and it was previously considered likely Valanginian to Hauterivian in age. However, it is now considered ...
(
Japan
Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...
). Early Cretaceous
South America
South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...
n taxon ''
Tijubina'', and possibly also ''
Olindalacerta'', might also fall within Polyglyphanodontia or be closely allied to the group, but if so, they would be two of only three
Gondwana
Gondwana () was a large landmass, often referred to as a supercontinent, that formed during the late Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic period (about 180 million years ago). The final stages ...
n examples of an otherwise Laurasian clade (the third one, and the only unambiguous one, being ''
Bicuspidon hogreli'' from the
Kem Kem Beds
The Kem Kem Group (commonly known as the Kem Kem beds) is a geological group in the Kem Kem region of eastern Morocco, whose strata date back to the Cenomanian stage of the Late Cretaceous. Its strata are subdivided into two geological formations, ...
of
Morocco
Morocco (),, ) officially the Kingdom of Morocco, is the westernmost country in the Maghreb region of North Africa. It overlooks the Mediterranean Sea to the north and the Atlantic Ocean to the west, and has land borders with Algeria to ...
). They produced a remarkable range of forms. Chamopsiids, including ''
Chamops
''Chamops'' is an extinct genus of polyglyphanodontian lizard from the Late Cretaceous-Early Eocene of North America. Fossils have been found in the Hell Creek Formation, Judith River Formation and Polecat Bench Formation of Montana, the Milk Ri ...
'', were characterized by large, blunt, crushing teeth, and were most likely omnivores. ''
Macrocephalosaurus'', from the Gobi Desert, was a specialized
herbivore
A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpart ...
; it grew to roughly a meter long and had multicusped, leaf-shaped teeth like those of modern iguanas. ''
Polyglyphanodon
''Polyglyphanodon'' is an extinct genus of Polyglyphanodontid lizard containing the species ''P. sternbergi'' from the Maastrichtian aged North Horn Formation of Utah
Utah ( , ) is a state in the Mountain West subregion of the Wester ...
'', from the Maastrichtian of Utah, was another herbivore, but its teeth formed a series of transverse blades, similar to those of ''
Trilophosaurus
''Trilophosaurus'' (Greek for "lizard with three ridges") is a lizard-like trilophosaurid allokotosaur known from the Late Triassic of North America. It was a herbivore up to 2.5 m long. It had a short, unusually heavily built skull, equipped wi ...
''. ''
Peneteius'' had remarkable, multicusped teeth, similar to those of mammals. The polyglyphanodontids first appear in the latter part of the Early Cretaceous in North America, and became extinct during the
Cretaceous-Paleogene extinction event. Polyglyphanodontians closely resembled the
teiid lizards, and purported teiid lizards from the Late Cretaceous appear to be polyglyphanodontians.
The only species known to have survived the
Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...
was ''
Chamops
''Chamops'' is an extinct genus of polyglyphanodontian lizard from the Late Cretaceous-Early Eocene of North America. Fossils have been found in the Hell Creek Formation, Judith River Formation and Polecat Bench Formation of Montana, the Milk Ri ...
'', which survived until the very early
Ypresian
In the geologic timescale the Ypresian is the oldest age (geology), age or lowest stage (stratigraphy), stratigraphic stage of the Eocene. It spans the time between , is preceded by the Thanetian Age (part of the Paleocene) and is followed by th ...
(
early Eocene
In the geologic timescale the Ypresian is the oldest age or lowest stratigraphic stage of the Eocene. It spans the time between , is preceded by the Thanetian Age (part of the Paleocene) and is followed by the Eocene Lutetian Age. The Ypresian i ...
).
Classification
![Tianyusaurus](https://upload.wikimedia.org/wikipedia/commons/6/65/Tianyusaurus.jpg)
A large-scale
phylogenetic
In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...
analysis of squamates conducted by Conrad (2008) found polyglyphanodontians (called Polyglyphanodontidae by Conrad) to be closely related to teiid lizards. In the
strict consensus tree recovered in the analysis, polyglyphanodontids were part of a
polytomy
An internal node of a phylogenetic tree is described as a polytomy or multifurcation if (i) it is in a rooted tree and is linked to three or more child subtrees or (ii) it is in an unrooted tree and is attached to four or more branches. A tr ...
(unresolved evolutionary relationship) with teiids,
gymnophthalmids, ''Chamops'' and
lacertids; in the
Adams consensus tree polyglyphanodontids were the sister group to teiids.
(Some other studies that recognize a close relationship between polyglyphanodontians and teiids use the name Borioteiioidea rather than Polyglyphanodontia, although Borioteiioidea encompasses only North American polyglyphanodontians.)
Conrad's analysis also recovered ''
Sineoamphisbaena'', a Cretaceous lizard that resembles legless
amphisbaenia
Amphisbaenia (called amphisbaenians or worm lizards) is a group of usually legless squamates, comprising over 200 extant species. Amphisbaenians are characterized by their long bodies, the reduction or loss of the limbs, and rudimentary eyes. As ...
n lizards, as a member of Polyglyphanodontidae.
On the other hand, a later large-scale phylogenetic analysis of fossil and living squamates published in 2012 by Gauthier ''et al.'' found that Polyglyphanodontia was not particularly closely related to teiids, but rather that it was the
sister taxon
In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree.
Definition
The expression is most easily illustrated by a cladogram:
Taxon A and t ...
of the clade containing the extinct marine
mosasaur
Mosasaurs (from Latin ''Mosa'' meaning the 'Meuse', and Greek ' meaning 'lizard') comprise a group of extinct, large marine reptiles from the Late Cretaceous. Their first fossil remains were discovered in a limestone quarry at Maastricht on th ...
s, their closest relatives and the major lizard group
Scleroglossa
Scleroglossa is a group of lizards that includes geckos, autarchoglossans (scincomorphs, anguimorphs, and varanoids), and amphisbaenians. Scleroglossa is supported by phylogenetic analyses that use morphological features (visible anatomical featu ...
. Because the first scleroglossans appear in the
Late Jurassic
The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 163.5 ± 1.0 to 145.0 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic strata.Owen 1987.
In European lithostratigraphy, the name ...
, polyglyphanodontians must also have originated in the Late Jurassic if this phylogeny is correct. However, polyglyphanodontians are limited to the Cretaceous, meaning that a long
ghost lineage
A ghost lineage is a hypothesized ancestor in a species lineage that has left no fossil evidence yet can be inferred to exist because of gaps in the fossil record or genomic evidence. The process of determining a ghost lineage relies on fossilized ...
may exist.
[ The primary analysis of Gauthier ''et al.'' (2012) did not find polyglyphanodontians and ''Sineoamphisbaena'' to be closely related; however, the authors noted that when all snake-like squamates and mosasaurs were removed from the analysis, and burrowing squamates were then added individually to it, ''Sineoamphisbaena'' grouped with polyglyphanodontians. Gauthier ''et al.'' (2012) considered it possible that ''Sineoamphisbaena'' was a burrowing polyglyphanodontian,][ though, agreeing with.][ Subsequent analyses based on ][ have also supported ''Sineoamphisbaenia'' as a polyglyphanodontian (the combined molecular and morphological analysis of Müller et al.;] in the morphology only analyses carried out by Wiens et al. but not their combined molecular and morphological analyses;[ and in morphology only analyses carried out by who were describing new polyglyphanodontians from Asia 'Funuisaurus'' and ''Tianyusaurus''.
A phylogenetic analysis conducted by Reeder ''et al.'' (2015) based on combined molecular and morphological data (based on ][) recovered Polyglyphanodontia as members of ]Toxicofera
Toxicofera (Greek for "those who bear toxins") is a proposed clade of scaled reptiles (squamates) that includes the Serpentes (snakes), Anguimorpha (monitor lizards, gila monster, and alligator lizards) and Iguania (iguanas, agamas, and chamel ...
; specifically, it was recovered as the sister group of Iguania
Iguania is an infraorder of squamate reptiles that includes iguanas, chameleons, agamids, and New World lizards like anoles and phrynosomatids. Using morphological features as a guide to evolutionary relationships, the Iguania are believed t ...
. Lee (2009) analyzed a combined molecular and morphological data set (based on earlier studies by Lee) and also had found polyglyphanodontians as the sister to iguanians but Lee's finding was not acknowledged by.[ Combined molecular and morphological data analyses using Conrad's data ][John Wiens, Caitlin Kuczynski, Ted Townsend, Tod Reeder, Daniel Mulcahy, and Jack Sites, Jr. "Combining phylogenomics and fossils in higher-level squamate reptile phylogeny: molecular data change the placement of fossil taxa. ''Syst Biol'' 59 (6), 674–688 (2010).] consistently found polyglyphanodontians as the sisters to teiioids.
References
{{Taxonbar, from=Q864131
Scincogekkonomorpha
Cretaceous reptiles of Asia
Cretaceous reptiles of North America
Fossil taxa described in 2000
Early Cretaceous first appearances
Late Cretaceous extinctions