Haasiophis
Encyclopedia
Haasiophis, consisting of the sole species Haasiophis terrasanctus, is an extinct genus
of snake
s with hind limb
s. It is one of three genera of Cenomanian
snakes known to have possessed hindlimbs.
"ophis", for snake . The species names is from the Latin
"terrasanctus" meaning "holy land".
in the Judean hills, near Ramallah
, 20 km north of Jerusalem, in the central West Bank
. This site also produced the type and only specimen for the sister genus Pachyrhachis
. This site is a limestone
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.
, and advanced traits found in macrostomatans
. The cranium shows a small premaxilla
which bears no teeth, while the maxilla
, palatine
, pterygoid
, and dentar bones host 73-75 teeth. The preorbital are of the skull, being small and slender, is similar to the preorbital area of pythonine snakes. The contact between the prefrontal and frontal
bones of the skull are very similar to ones found in the sister genus Pachyrhachis
and the unrelated Dinilysia
. Due to the tail of the specimen being missing, the total vertebrae is 199, plus fragments of a 200th, with the rib cage extending from the 5th to the 154th vertebrae. Lymphapophyses (forked 'cloacal' 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
, bony thickening and growth.
rib or vertebrae. Also like Pachyrhachis there is no preserved indication of a connection between the vertebral column and the pelvic 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
, and fibula are preserved though the tibia is disarticulated slightly. The foot is composed of three tarsal ossification
s and five metatarsals. 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.
Based on cladistic analysis of skull features, Haasiophis and it sister genera are indicated to be 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 fist is the secondary gaining 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 Pachyophiidae family, and the complexity of snake evolution
ary taxonomy
is not enough to favor one option over the other.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of snake
Snake
Snakes are elongate, legless, carnivorous reptiles of the suborder Serpentes that can be distinguished from legless lizards by their lack of eyelids and external ears. Like all squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales...
s with hind limb
Hind limb
A hind limb is a posterior limb on an animal. When referring to quadrupeds, the term hind leg is often instead used....
s. It is one of three genera of Cenomanian
Cenomanian
The Cenomanian is, in the ICS' geological timescale the oldest or earliest age of the Late Cretaceous epoch or the lowest stage of the Upper Cretaceous series. An age is a unit of geochronology: it is a unit of time; the stage is a unit in the stratigraphic column deposited during the corresponding...
snakes known to have possessed hindlimbs.
Etymology
The genus was named in honor of the late paleontologist Georg Haas, who first began work in the fossils of Ein Yabrud and started the description of the genus before he died, plus the GreekGreek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
"ophis", for snake . The species names is from the Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
"terrasanctus" meaning "holy land".
Specimen material
H.terrasanctus is known from a single fossil discovered at Ein YabrudEin Yabrud
Ein Yabrud is a 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. According to the Palestinian Central Bureau of Statistics the town had a population of 3,000...
in the Judean hills, near Ramallah
Ramallah
Ramallah is a Palestinian city in the central West Bank located 10 kilometers north of Jerusalem, adjacent to al-Bireh. It currently serves as the de facto administrative capital of the Palestinian National Authority...
, 20 km north of Jerusalem, in the central West Bank
West Bank
The West Bank ) of the Jordan River is the landlocked geographical eastern part of the Palestinian territories located in Western Asia. To the west, north, and south, the West Bank shares borders with the state of Israel. To the east, across the Jordan River, lies the Hashemite Kingdom of Jordan...
. This site also produced the type and only specimen for the sister genus Pachyrhachis
Pachyrhachis
Pachyrhachis is an extinct genus of snake with well developed hind legs known from fossils discovered Ein Yabrud, near Ramallah, in the central West Bank. It is one of three genera of Cenomanian snakes with hindlimbs. Many of today's modern pythons and boas still have small bone spurs, where limbs...
. This site is a limestone
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
carbonate
Carbonate
In chemistry, a carbonate is a salt of carbonic acid, characterized by the presence of the carbonate ion, . The name may also mean an ester of carbonic acid, an organic compound containing the carbonate group C2....
which deposited in a low-energy marine
Marine (ocean)
Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...
platform environment. The only known specimen of H.terrasanctus, housed in the collections of the Hebrew University of Jerusalem
Hebrew University of Jerusalem
The Hebrew University of Jerusalem ; ; abbreviated HUJI) is Israel's second-oldest university, after the Technion – Israel Institute of Technology. The Hebrew University has three campuses in Jerusalem and one in Rehovot. The world's largest Jewish studies library is located on its Edmond J...
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 the cranium is described as showing a mix of basal characters, like those found in pipe snakesAniliidae
The Aniliidae are a monotypic family created for the monotypic genus Anilius that contains the species A. scytale, found in South America. This snake possesses a vestigial pelvic girdle that is visible as a pair of cloacal spurs. It is ovoviviparous. The diet consists mainly of amphibians and...
, and advanced traits found in macrostomatans
Snake
Snakes are elongate, legless, carnivorous reptiles of the suborder Serpentes that can be distinguished from legless lizards by their lack of eyelids and external ears. Like all squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales...
. The cranium shows a small premaxilla
Premaxilla
The incisive bone is the portion of the maxilla adjacent to the incisors. It is a pair of small cranial bones at the very tip of the jaws of many animals, usually bearing teeth, but not always. They are connected to the maxilla and the nasals....
which bears no teeth, while the maxilla
Maxilla
The maxilla is a fusion of two bones along the palatal fissure that form the upper jaw. This is similar to the mandible , which is also a fusion of two halves at the mental symphysis. Sometimes The maxilla (plural: maxillae) is a fusion of two bones along the palatal fissure that form the upper...
, palatine
Palatine
A palatine or palatinus is a high-level official attached to imperial or royal courts in Europe since Roman times...
, pterygoid
Pterygoid
Pterygoid can refer to:* Pterygoid processes of the sphenoid bone** The Lateral pterygoid plate by it* a muscle such as Lateral pterygoid muscle or Medial pterygoid muscle* a branch of the Mandibular nerve...
, and dentar bones host 73-75 teeth. The preorbital are of the skull, being small and slender, is similar to the preorbital area of pythonine snakes. The contact between the prefrontal and frontal
Frontal bone
The frontal bone is a bone in the human skull that resembles a cockleshell in form, and consists of two portions:* a vertical portion, the squama frontalis, corresponding with the region of the forehead....
bones of the skull are very similar to ones found in the sister genus Pachyrhachis
Pachyrhachis
Pachyrhachis is an extinct genus of snake with well developed hind legs known from fossils discovered Ein Yabrud, near Ramallah, in the central West Bank. It is one of three genera of Cenomanian snakes with hindlimbs. Many of today's modern pythons and boas still have small bone spurs, where limbs...
and the unrelated Dinilysia
Dinilysia
Dinilysia is an extinct genus of snake from the Late Cretaceous of South America. The snake reached a length of 6-10 feet and preyed on smaller animals...
. Due to the tail of the specimen being missing, the total vertebrae is 199, plus fragments of a 200th, with the rib cage extending from the 5th to the 154th vertebrae. Lymphapophyses (forked 'cloacal' 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
Pachyostosis is a condition in vertebrate animals in which the bones experience a thickening, resulting in unusually solid bone structure with little to no marrow. It occurs in both terrestrial and aquatic vertebrates, such as manatees and dugongs, plesiosaurs, and members of the Dinocephalia...
, bony thickening and growth.
Hind limbs
Along with is sister genus Pachyrhachis, Haasiophis does not possess either a sacralSacral
Sacral may refer to:*sacred*sacrum...
rib or vertebrae. Also like Pachyrhachis there is no preserved indication of a connection between the vertebral column and the pelvic 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
Tarsus (skeleton)
In tetrapods, the tarsus is a cluster of articulating bones in each foot situated between the lower end of tibia and fibula of the lower leg and the metatarsus. In the foot the tarsus articulates with the bones of the metatarsus, which in turn articulate with the bones of the individual toes...
, tibia
Tibia
The tibia , shinbone, or shankbone is the larger and stronger of the two bones in the leg below the knee in vertebrates , and connects the knee with the ankle bones....
, and fibula are preserved though the tibia is disarticulated slightly. The foot is composed of three tarsal ossification
Ossification
Ossification is the process of laying down new bone material by cells called osteoblasts. It is synonymous with bone tissue formation...
s and five metatarsals. 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 indication of Haasiophis being a juvenile specimen of Pachyrhachis. The small overall size, underdevelopment of the tarsal ossifications, less pachyostosis extent, 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 distinct. The neural spines of Pachyrhachis are much taller in comparison and the rib shape is quite distinct. Therefore while regarded as being very close in relationship the two are different genera.Based on cladistic analysis of skull features, Haasiophis and it sister genera are indicated to be either a sister group to or basal members of the macrostomatan
Snake
Snakes are elongate, legless, carnivorous reptiles of the suborder Serpentes that can be distinguished from legless lizards by their lack of eyelids and external ears. Like all squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales...
clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
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
Pachyophiidae
Pachyophiidae is an extinct family of snakes which lived during the Cenomanian stage of the Late Cretaceous. The family was erected in 1923 by F. Nopcsa as "Pachyophiidae", which was corrected to the current name Pachyophiidae in 1999 by M...
. The fist is the secondary gaining 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 Pachyophiidae family, and the complexity of snake evolution
Evolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...
ary taxonomy
Taxonomy
Taxonomy is the science of identifying and naming species, and arranging them into a classification. The field of taxonomy, sometimes referred to as "biological taxonomy", revolves around the description and use of taxonomic units, known as taxa...
is not enough to favor one option over the other.
See also
Other known fossil snakes with legs:- EupodophisEupodophisEupodophis is an extinct genus of snake from the Late Cretaceous period. It has two small hind legs and is considered a transitional form between Cretaceous lizards and limbless snakes. The feature, described as vestigial, was most likely useless to Eupodophis. The type species Eupodophis...
- Najash
- PachyrhachisPachyrhachisPachyrhachis is an extinct genus of snake with well developed hind legs known from fossils discovered Ein Yabrud, near Ramallah, in the central West Bank. It is one of three genera of Cenomanian snakes with hindlimbs. Many of today's modern pythons and boas still have small bone spurs, where limbs...