''Haasiophis'', consisting of the sole species ''Haasiophis terrasanctus'', is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

snake Snakes are elongated, limbless, carnivorous reptiles of the suborder Serpentes . Like all other squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales. Many species of snakes have skulls with several more j ...

s with

hind limb A hindlimb or back limb is one of the paired articulated appendages (limbs) attached on the caudal ( posterior) end of a terrestrial tetrapod vertebrate's torso.http://www.merriam-webster.com/medical/hind%20limb, Merriam Webster Dictionary-Hindli ...

s. It is one of three genera of Cenomanian snakes known to have possessed hindlimbs.

Etymology

The genus was named in honor of the late

paleontologist Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of fossi ...

Georg Haas, who first began work in the fossils of Ein Yabrud and started the description of the genus before he died, plus the

Greek Greek may refer to: Greece 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 ...

"ophis", for snake . The species names is from the

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

"terrasanctus" meaning "holy land".

Specimen material

''H. terrasanctus'' is known from a single fossil discovered at

Ein Yabrud Ein Yabrud ( ar, عين يبرود) is a Palestinian people, Palestinian town in the Ramallah and al-Bireh Governorate in the central West Bank. It is located approximately 7 km northeast of the city of Ramallah and its elevation is 800 m ...

in the

Judean hills The Judaean Mountains, or Judaean Hills ( he, הרי יהודה, translit=Harei Yehuda) or the Hebron Mountains ( ar, تلال الخليل, translit=Tilal al-Khalīl, links=, lit=Hebron Mountains), is a mountain range in Palestine and Israel wh ...

, near Ramallah, 20 km north of

Jerusalem Jerusalem (; he, יְרוּשָׁלַיִם ; ar, القُدس ) (combining the Biblical and common usage Arabic names); grc, Ἱερουσαλήμ/Ἰεροσόλυμα, Hierousalḗm/Hierosóluma; hy, Երուսաղեմ, Erusałēm. i ...

, in the central

West Bank The West Bank ( ar, الضفة الغربية, translit=aḍ-Ḍiffah al-Ġarbiyyah; he, הגדה המערבית, translit=HaGadah HaMaʽaravit, also referred to by some Israelis as ) is a landlocked territory near the coast of the Mediter ...

. This site also produced the type and only specimen for the sister genus ''

Pachyrhachis ''Pachyrhachis'' (from el, παχύς , 'thick' and el, ῥάχῐς , 'spine') is an extinct genus of snake with well developed hind legs known from fossils discovered in Ein Yabrud, near Ramallah, in the central West Bank. It is a relatively ...

''. et al. 2003 "The Anatomy and Relationships of Haasiophis terrasanctus, a Fossil Snake with Well-Developed Hind Limbs from the Mid-Cretaceous of the Middle East" ''Journal of Paleontology'' 77(3):536-558 This site is a

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

carbonate A carbonate is a salt of carbonic acid (H2CO3), characterized by the presence of the carbonate ion, a polyatomic ion with the formula . The word ''carbonate'' may also refer to a carbonate ester, an organic compound containing the carbonate ...

which deposited in a low-energy marine platform environment. The only known specimen of ''H. terrasanctus'', housed in the collections of the Hebrew University of Jerusalem as specimen HUJ-Pal. EJ 695., measures 88 cm, missing only the tip of the tail, and is considered a small snake.

Skull

The skull is well preserved though slightly compressed. In the

type description A species description is a formal description of a newly discovered species, usually in the form of a scientific paper. Its purpose is to give a clear description of a new species of organism and explain how it differs from species that have be ...

the cranium is described as showing a mix of basal characters, like those found in pipe snakes, and advanced traits found in macrostomatans. The cranium shows a small

premaxilla The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammal has ...

which bears no teeth, while the

maxilla The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. T ...

palatine A palatine or palatinus (in Latin; plural ''palatini''; cf. derivative spellings below) is a high-level official attached to imperial or royal courts in Europe since Roman times.

pterygoid Pterygoid, from the Greek for 'winglike', may refer to: * Pterygoid bone, a bone of the palate of many vertebrates * Pterygoid processes of the sphenoid bone ** Lateral pterygoid plate ** Medial pterygoid plate * Lateral pterygoid muscle * Medi ...

, and dentar bones host 73-75 teeth. The preorbital area of the skull, being small and slender, is similar to the preorbital area of pythonine snakes. The contact between the prefrontal and

frontal Front may refer to: Arts, entertainment, and media Films * ''The Front'' (1943 film), a 1943 Soviet drama film * ''The Front'', 1976 film Music * The Front (band), an American rock band signed to Columbia Records and active in the 1980s and e ...

bones of the skull are very similar to ones found in the sister genus ''

'' and the unrelated ''

Dinilysia ''Dinilysia'' (meaning "terrible ilysia") is an extinct genus of snake from the Late Cretaceous ( Coniacian) of South America. ''Dinilysia'' was a relatively large ambush predator, measuring approximately long. The skull morphology of ''Dinilys ...

''. Due to the tail of the specimen being missing, the total

vertebrae The spinal column, a defining synapomorphy shared by nearly all vertebrates, Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristi ...

is 199, plus fragments of a 200th, with the rib cage extending from the 5th to the 154th vertebrae. Lymphapophyses (forked '

cloacal In animal anatomy, a cloaca ( ), plural cloacae ( or ), is the posterior orifice that serves as the only opening for the digestive, reproductive, and urinary tracts (if present) of many vertebrate animals. All amphibians, reptiles and birds, a ...

' ribs) are found beginning on the 155th vertebrae and continuing to the 160th. The ribs from the 45-48th and 105-108th vertebrae show signs of

pachyostosis Pachyostosis is a non-pathological condition in vertebrate animals in which the bones experience a thickening, generally caused by extra layers of lamellar bone. It often occurs together with bone densification (osteosclerosis), reducing inner ca ...

, bony thickening and growth.

Hind limbs

Along with its sister genus ''Pachyrhachis'', ''Haasiophis'' does not possess either a

sacral Sacral may refer to: *Sacred Sacred describes something that is dedicated or set apart for the service or worship of a deity; is considered worthy of spiritual respect or devotion; or inspires awe or reverence among believers. The property ...

rib or vertebrae. Also like ''Pachyrhachis'' there is no preserved indication of a connection between the vertebral column and the

pelvic The pelvis (plural pelves or pelvises) is the lower part of the trunk, between the abdomen and the thighs (sometimes also called pelvic region), together with its embedded skeleton (sometimes also called bony pelvis, or pelvic skeleton). The p ...

girdle. The pelvic girdle is partly obscured by overlaying bones reducing the detail which can be seen. Radiographs of the specimen reveal ''H. terrasanctus'' possessing a simple triradiate similar to that possessed by ''Pachyrhachis''. Both femurs are preserved with the specimen, but the rest of the right leg is missing. The left zeugopodium, tarsus,

tibia The tibia (; ), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outside of the tibia); it connects ...

, and

fibula The fibula or calf bone is a leg bone on the lateral side of the tibia, to which it is connected above and below. It is the smaller of the two bones and, in proportion to its length, the most slender of all the long bones. Its upper extremity i ...

are preserved though the tibia is disarticulated slightly. The foot is composed of three tarsal

ossification Ossification (also called osteogenesis or bone mineralization) in bone remodeling is the process of laying down new bone material by cells named osteoblasts. It is synonymous with bone tissue formation. There are two processes resulting in ...

s and five

metatarsal The metatarsal bones, or metatarsus, are a group of five long bones in the foot, located between the tarsal bones of the hind- and mid-foot and the phalanges of the toes. Lacking individual names, the metatarsal bones are numbered from the me ...

s. The tarsal ossifications do not show signs that the bones were connected to each other during life. Traces of two phalanges are discernible behind metatarsals two and three.

Taxonomic position

Several of the skeletal characters of ''Haasiophis'' may be interpreted as an indication that ''Haasiophis'' is a juvenile specimen of ''Pachyrhachis''. The small overall size, underdevelopment of the tarsal ossifications, less extensive pachyostosis, and larger proportional size of the tibia and fibula are all possible traits of a juvenile. However the skull and tooth structures of ''Pachyrhachis'' and ''Haasiophis'' are markedly different. The

neural spine The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic ...

s of ''Pachyrhachis'' are much taller in comparison and the rib shape is quite distinct. Therefore, while regarded as very closely related, the two are different genera. Based on

cladistic Cladistics (; ) is an approach to biological classification in which organisms are categorized in groups ("clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is typically shared derived char ...

analysis of skull features, ''Haasiophis'' and its sister genera are indicated as either a sister group to, or basal members of, the macrostomatan clade of snakes. This is supported by the general characteristics of the skeleton. The presence of the hind limbs presents a problem with this placement however. There are two major ideas for the presence of hind limbs in Pachyophiidae. The first is the secondary regaining of the limbs from legless ancestors, while the second is the possibility of multiple episodes of leg loss in snakes. Unfortunately the current number of specimens from the family Pachyophiidae, and the complexity of snake

evolution Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation ...

ary

taxonomy Taxonomy is the practice and science of categorization or classification. A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. ...

are not enough to favor one option over the other.

References