''Powellophis'' is a

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 extinct madtsoiid

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 ...

from the

Mealla Formation The Mealla Formation is a geological formation of the Santa Bárbara Subgroup, part of the Salta Group in the Salta Basin in northwestern Argentina whose strata date back to the Middle to Late Paleocene of the Paleogene. Description The Me ...

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

, dating back to the

Paleocene The Paleocene ( ), or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), ...

. It is a

monospecific In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispe ...

genus, with the only

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

being ''P. andina''.

Discovery and naming

The

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

of ''Powellophis'', specimen PVL 4714, preserves a nearly complete and articulated

skeleton A skeleton is the structural frame that supports the body of most animals. There are several types of skeletons, including the exoskeleton, which is a rigid outer shell that holds up an organism's shape; the endoskeleton, a rigid internal fra ...

in nine continuous

siltstone Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility. Although its permeabil ...

blocks. However, only blocks 4714-2 to 4714-9 were available for study. This means that other blocks from the holotype specimen are not included in the paper naming the genus. The animal shares some features of its

vertebral Each vertebra (: vertebrae) is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spina ...

morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines *Morphology (archaeology), study of the shapes or forms of artifacts *Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies, ...

with other mid to large sized madtsoiids. ''Powellophis'' is quantitatively estimated to have been around in length based on measures of vertebrae and total length in extant snakes. The genus name ''Powellophis'' means "

Jaime Powell Jaime Eduardo Powell (January 13, 1953 – February 1, 2016) was an Argentine paleontologist who described the titanosaur sauropod dinosaur taxa ''Aeolosaurus'' and found evidence that titanosaurs have osteoderms. Research Powell described the f ...

's Snake". The name is constructed from the words Powell and , the former in honor of the late Dr. Jaime Powell who recovered the specimen and the latter meaning snake in

Ancient Greek Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek ...

. The specific name ''andina'' is named for the

Andes The Andes ( ), Andes Mountains or Andean Mountain Range (; ) are the List of longest mountain chains on Earth, longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range ...

region of Northwestern Argentina, where the

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 ...

remains of the animal were discovered.

Classification

In the

phylogeny A phylogenetic tree or phylogeny is a graphical representation which shows the evolutionary history between a set of species or Taxon, taxa during a specific time.Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, M ...

from Garberoglio, Triviño & Albino (2022), ''Powellophis'' is recovered as a sister taxon to '' Eomadtsoia'' and a basal member of a clade that includes most large bodied and gigantic members of the group like ''

Gigantophis ''Gigantophis'' is an extinct genus of giant snake containing a single species, ''G. garstini''. Before the Paleocene constrictor genus '' Titanoboa'' was described from Colombia in 2009, ''G. garstini'' was regarded as the largest snake ever r ...

'', ''

Wonambi ''Wonambi'' is an extinct genus of madtsoiid snakes that lived in late Neogene to late Quaternary Australia. Species of ''Wonambi'' were constrictor snakes unrelated to Australian pythons. Taxonomy and naming ''Wonambi naracoortensis'' was ...

'', and '' Madtsoia''. A clade with similar genus composition, although lacking ''Powellophis'', was recovered in 2019 by Gómez, Garberoglio & Rougier.

Paleoenvironment

''Powellophis'' inhabited the Mealla Formation, dating to the middle to late paleocene of Northwestern Argentina. The preserved vertebrate fauna from this formation includes teleostean fishes, pelomedusid turtles, sebecid crocodillians and notoungulate mammals. The environmental interpretation indicates the presence of a sandy, meandering fluvial system with low energy and low sinuosity, mud dominated floodplains with paleosol development, and shallow, freshwater clastic lakes with periods of subaerial exposure.

References

Paleocene reptiles of South America Fossils of Argentina Fossil taxa described in 2022 Selandian Thanetian Prehistoric reptile genera Paleogene Argentina {{paleo-reptile-stub