''Tetrapodophis'' (
Greek
Greek may refer to:
Anything of, from, or related to Greece, a country in Southern Europe:
*Greeks, an ethnic group
*Greek language, a branch of the Indo-European language family
**Proto-Greek language, the assumed last common ancestor of all kno ...
meaning "four-footed snake") is an extinct
genus
Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
of
lizard
Lizard is the common name used for all Squamata, squamate reptiles other than snakes (and to a lesser extent amphisbaenians), encompassing over 7,000 species, ranging across all continents except Antarctica, as well as most Island#Oceanic isla ...
from the
Early Cretaceous
The Early Cretaceous (geochronology, geochronological name) or the Lower Cretaceous (chronostratigraphy, chronostratigraphic name) is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 143.1 ...
(
Aptian
The Aptian is an age (geology), age in the geologic timescale or a stage (stratigraphy), stage in the stratigraphic column. It is a subdivision of the Early Cretaceous, Early or Lower Cretaceous epoch (geology), Epoch or series (stratigraphy), S ...
) aged
Crato Formation
The Crato Formation is a geologic formation (stratigraphy), formation of Early Cretaceous (Aptian) age in northeastern Brazil's Araripe Basin. It is an important Lagerstätten, Lagerstätte (undisturbed fossil accumulation) for palaeontology, pa ...
of Brazil. It has an elongated snake-like body, with four disproportionately short limbs.
''Tetrapodophis'' has been considered by some authors to be one of the oldest members of
Ophidia; the taxonomic group which includes
snake
Snakes are elongated limbless reptiles of the suborder Serpentes (). Cladistically squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales much like other members of the group. Many species of snakes have s ...
s and some of their closest extinct relatives.
However, this classification has been disputed by some other authors,
who identify ''Tetrapodophis'' as a
dolichosaurid. The exact phylogenetic placement of Dolichosauridae is also disputed. Dolichosaurids could be related to Ophidia, which would mean that ''Tetrapodophis'' is indeed related to snakes, albeit more distantly than previously thought. Alternatively, dolichosaurids could be more closely related to
mosasaurs.
Description

''Tetrapodophis'' possesses small yet well-developed
fore- and
hindlimbs like a lizard and a long body similar to a snake, around in length.
Nevertheless, it shares many characteristics with modern snakes, including an elongate body, short tail, broad belly scales, a skull with a short snout and long
braincase, curved jaws, and sharp hooked teeth. BMMS BK 2-2 contains bones of another animal in its gut, indicating that ''Tetrapodophis'' was
carnivorous
A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose nutrition and energy requirements are met by consumption of animal tissues (mainly mu ...
like most snakes. Other features such as short
neural spines suggest that ''Tetrapodophis'' was adapted to burrowing, lending support to the hypothesis that snakes evolved in terrestrial environments (another hypothesis posits that they evolved in aquatic environments).
The high number of vertebrae (upwards of 150) in ''Tetrapodophis'' and snakes is not seen in other burrowing reptiles with elongate bodies and reduced or absent limbs, meaning that it is most likely not an adaptation for a serpentine form of movement.
[
]
Discovery and controversy
The type species
In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...
, ''Tetrapodophis amplectus'', was named in 2015 on the basis of a complete skeleton (BMMS BK 2-2) preserved on a limestone
Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...
slab in the Bürgermeister Müller Museum in Solnhofen, Germany, which was labeled as "unknown fossil
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...
" until its importance was recognized by paleontologist
Paleontology, also spelled as palaeontology or palæontology, is the scientific study of the life of the past, mainly but not exclusively through the study of fossils. Paleontologists use fossils as a means to classify organisms, measure geolo ...
David Martill when he visited Germany in 2012, and housed in a private collection in a private in a museum in Solnhofen. The fossil had been in the hands of the private collector for "several decades" prior to the publication. While no locality information was provided for the specimen, based on characteristics of the rock it is thought to come from the Early Cretaceous Crato Formation
The Crato Formation is a geologic formation (stratigraphy), formation of Early Cretaceous (Aptian) age in northeastern Brazil's Araripe Basin. It is an important Lagerstätten, Lagerstätte (undisturbed fossil accumulation) for palaeontology, pa ...
of Northeast Brazil. Brazil's laws do not allow the removal of fossils from its territory since 1942, nor that studies on them be conducted without the participation of at least one Brazilian scientist. Due to a lack of information regarding the provenance of the fossil, it was possible that the fossil had been illegally exported from Brazil. This caused controversy among Brazilian paleontologists, and sparked a legal investigation by the Brazilian government. According to lead author Martill, fossils from the Crato Formation are widely illegally collected and exported from Brazil due to corruption in the country, and are found in fossil shops and museums all over the world, and that if current regulations were followed many fossils would simply be destroyed rather than collected.
When the fossil was collected is unknown. Dave Martill asserted in an interview to a Brazilian journalist that it was possible that the fossil was exported prior to 1942, but stated that ultimately he didn't "care a damn how r whenthe fossil came from Brazil", saying that it was irrelevant to its scientific significance. Martill stated that he was "critical of all laws that interfere with the science of paleontology; and blanket bans on fossil collecting are indiscriminatory and only hinder science ... They also lead to xenophobia -- Brazil fossils for Brazilians, British fossils for Brits. It should be fossils for all. No countries existed when the animals were fossilized." When asked why he did not include a Brazilian scientist on the study, Martill remarked that he was unaware of any Brazilian snake researchers when writing the study (though he later became aware of one following the controversy), but followed with "But what difference would it make? I mean, do you want me also to have a black person on the team for ethnicity reasons, and a cripple and a woman, and maybe a homosexual too just for a bit of all round balance? … If you invite people because they are Brazilian then people will think that every Brazilian author on a scientific paper is there because he is Brazilian and not because he is a clever scientist." Martill remarked several years later in 2020 that he felt his comments in the interview were poorly worded. Nicholas Longrich, a co-author of the study, remarked that he would like to see the fossil returned to Brazil.
Aside from the export issues, the fact that the specimen was in a private collection when described also caused controversy, and the owner of the fossil reportedly made it difficult for later researchers to study the specimen. In 2024, the fossil of ''Tetrapodophis'' was donated to National Museum of Brazil
National may refer to:
Common uses
* Nation or country
** Nationality – a ''national'' is a person who is subject to a nation, regardless of whether the person has full rights as a citizen
Places in the United States
* National, Maryland, ...
.
Classification
A phylogenetic analysis
In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical data ...
published alongside the original 2015 description of ''Tetrapodophis'' places it as a close relative of other lizards, but outside the crown group
In phylogenetics, the crown group or crown assemblage is a collection of species composed of the living representatives of the collection, the most recent common ancestor of the collection, and all descendants of the most recent common ancestor ...
Serpentes, meaning that ''Tetrapodophis'' branched off before the most recent common ancestor
A most recent common ancestor (MRCA), also known as a last common ancestor (LCA), is the most recent individual from which all organisms of a set are inferred to have descended. The most recent common ancestor of a higher taxon is generally assu ...
of all living snakes. Below is a cladogram
A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...
from that analysis:[
The interpretation of ''Tetrapodophis amplectus'' as an early ]fossorial
A fossorial animal () is one that is adapted to digging and which lives primarily (but not solely) underground. Examples of fossorial vertebrates are Mole (animal), moles, badgers, naked mole-rats, meerkats, armadillos, wombats, and mole salamand ...
snake was challenged by Caldwell ''et al.'' (2016), who considered it more likely to be a dolichosaurid squamate
Squamata (, Latin ''squamatus'', 'scaly, having scales') is the largest Order (biology), order of reptiles; most members of which are commonly known as Lizard, lizards, with the group also including Snake, snakes. With over 11,991 species, it i ...
related to mosasaur
Mosasaurs (from Latin ''Mosa'' meaning the 'Meuse', and Ancient Greek, Greek ' meaning 'lizard') are an extinct group of large aquatic reptiles within the family Mosasauridae that lived during the Late Cretaceous. Their first fossil remains wer ...
s. A position supported by later analysis in 2018[ and in 2021.][
Cladogram after Caldwell et. al. 2021:][
However, a study in 2023 again supported its position as a stem-snake, finding it to be unrelated to mosasaurs.]
References
External links
*
''Tetrapodophis'' as it may have been in life
Scientists Discover Four-Legged Snake Fossil
On: SciTechDaily, Source: University of Portsmouth. 2 August 2015
* Susan Evans:
Four legs too many?
" In: Science Vol. 349 no. 6246 pp. 374–375. 24 July 2015; doi:10.1126/science.aac5672
{{Taxonbar, from=Q20729892
Early Cretaceous reptiles of South America
Cretaceous Brazil
Fossils of Brazil
Crato Formation
Fossil taxa described in 2015
Cretaceous lizards
Dolichosauridae