Haasiophis, consisting of the sole species
Haasiophis terrasanctus, is an extinct
genusIn biology, a genus is a taxonomic unit used in the classification of living and fossil organisms. The term comes from Latin genus "descent, family, type, gender" , cognate with – genos, "race, stock, kin" ..In addition, genus is a taxonomic rank in the hierarchy In biology, a genus (plural:...
of
snakeSnakes 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 limbA 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
CenomanianThe 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.
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 , an independent branch of the Indo-European family of languages, is the language of the Greeks. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. In its ancient form, it is the language of classical...
"ophis", for snake .
Haasiophis, consisting of the sole species
Haasiophis terrasanctus, is an extinct
genusIn biology, a genus is a taxonomic unit used in the classification of living and fossil organisms. The term comes from Latin genus "descent, family, type, gender" , cognate with – genos, "race, stock, kin" ..In addition, genus is a taxonomic rank in the hierarchy In biology, a genus (plural:...
of
snakeSnakes 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 limbA 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
CenomanianThe 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 , an independent branch of the Indo-European family of languages, is the language of the Greeks. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. In its ancient form, it is the language of classical...
"ophis", for snake . The species names is from the
LatinLatin is an Italic language originally spoken in Latium and Ancient Rome. Through the Roman conquest, Latin spread throughout the Mediterranean and a large part of Europe...
"terrasanctus" meaning "holy land".
Specimen material
H.terrasanctus is known from a single fossil discovered at
Ein YabrudEin 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
RamallahRamallah is a Palestinian city in the central West Bank adjacent to al-Bireh with a population nearly 25,500...
, 20 km north of
JerusalemJerusalem is the capital of Israel and its largest city in both population and area, with a population of 747,600 residents over an area of if disputed East Jerusalem is included...
, in the central
West BankThe West Bank is a landlocked territory and is the eastern part of the Palestinian territories; on the west bank of the River Jordan in the Middle East. To the west, north, and south, the West Bank shares borders with the state of Israel, which maintains the security of this area. To the east,...
. This site also produced the type and only specimen for the sister genus
PachyrhachisPachyrhachis 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
limestoneLimestone is a sedimentary rock composed largely of the mineral calcite . The deposition of limestone strata is often a by-product and indicator of biological activity in the geologic record...
carbonateIn chemistry, a carbonate is a salt or ester of carbonic acid, characterized by the presence of the carbonate ion, or a carbonate functional group O=C2....
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 JerusalemThe Hebrew University of Jerusalem is Israel's oldest university....
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 snakesThe 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
macrostomatansSnakes 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
premaxillaThe 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
maxillaThe 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 is sometimes called "upper maxilla", with the mandible being the "lower maxilla"...
,
palatineA palatine or palatinus was a high-level official attached to imperial or royal courts in Europe since Roman times...
,
pterygoidPterygoid 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 bones of the skull are very similar to ones found in the sister genus
PachyrhachisPachyrhachis 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
DinilysiaDinilysia is an extinct genus of snake from the Late Cretaceous of South America.-In Popular Culture:The BBC website confirms Dinilysia as appearing in the last episode of the famous 1999 documentary series Walking with Dinosaurs as the snake encountered by two infant Tyrannosaurus, although the...
. 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
pachyostosisPachyostosis 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 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,
tarsusIn tetrapods, the tarsus are the cluster of bones in the foot between the tibia and fibula and the metatarsus. The bones of the tarsus do not belong to individual toes, whereas those of the metatarsus do...
,
tibiaThe 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.The tibia is named for the greek aulos flute, also known as a tibia.-In humans:...
, and
fibulaThe fibula or calf bone is a bone located on the lateral side of the tibia, with 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...
are preserved though the tibia is disarticulated slightly. The foot is composed of three tarsal
ossificationOssification is a medical term that is synonymous with bone tissue formation. Endochondral ossification and intramembranous ossification are two processes resulting in the formation of normal, healthy bone tissue. Heterotopic ossification is a process resulting in the formation of bone tissue, that...
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
macrostomatanSnakes 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...
cladeA clade is a term used in modern alpha taxonomy, the scientific classification of living and fossil organisms, to describe a monophyletic group, defined as a group consisting of a single common ancestor and all its descendants.[The term "monophyletic group" is used in this article...]
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
PachyophiidaePachyophiidae 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
evolutionIn biology, evolution is change in the genetic material of a population of organisms from one generation to the next. Though changes produced in any one generation are normally small, differences accumulate with each generation and can, over time, cause substantial changes in the population, a...
ary
taxonomyTaxonomy is the practice and science of classification. The word finds its roots in the Greek , taxis and , nomos...
is not enough to favor one option over the other.
See also
Other known fossil snakes with legs:
- Eupodophis
Eupodophis is an extinct genus of snake from the Late Cretaceous period. The only species , E. descouensi, had two legs, and is a "transitional form" between Cretaceous lizards and limbless snake....
- Najash