Scolecophidia

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Scolecophidia
Temporal range: 87.8–0  Ma
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O
S
D
C
P
T
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K
Pg
N
Late Cretaceous - present (but see text)
Ramphotyphlops braminus jja.jpg
Brahminy blind snake,
Ramphotyphlops braminus
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Suborder: Serpentes
Infraorder: Scolecophidia
Cope, 1864 [1]
Families

See text

The Scolecophidia, commonly known as blind snakes or thread snakes, [2] are an infraorder [2] of snakes. [3] They range in length from 10 to 100 centimeters (4 to 40 inches). All are fossorial (adapted for burrowing). [4] Five families and 39 genera are recognized. [5] The Scolecophidia infraorder is most-likely paraphyletic (with the family Anomalepididae recovered with strong support as sister clade to the 'typical snakes'). [6]

Contents

Taxonomy

The infraorder name Scolecophidia derives from the two Ancient Greek words σκώληξ or σκώληκος (skṓlēx, genitive skṓlēkos), meaning "earthworm", and ὄφις (óphis), meaning "snake". [7] [8] It refers to their shape and fossorial lifestyle.

Families

Family [2] Authority [2] Genera [5] Common name [2] Geographic range [1]
Anomalepididae Taylor, 19394primitive blind snakesSouthern Central America and South America
Gerrhopilidae Vidal, Wynn, Donnellan & Hedges, 2010 [9] 2Indo-Malayan blind snakes India, Southeast Asia, Indonesia, the Philippines, and New Guinea [10]
Leptotyphlopidae Stejneger, 189213slender blind snakes or threadsnakes Africa, western Asia, and the Americas
Typhlopidae Merrem, 182018long-tailed blind snakesMost tropical and many subtropical regions all over the world
Xenotyphlopidae Vidal, Vences, Branch & Hedges, 2010 [9] 1Malagasy blind snakes Madagascar

Evolution

Despite only having fossils as early as the Cretaceous, Scolecophidia itself likely originated in the Middle Jurassic, with Anomalepididae, Leptotyphlopidae, and Typhlopoidea diverging from one another during the Late Jurassic. Within Typhlopoidea, Gerrhopilidae likely diverged from the Xenotyphlopidae-Typhlopidae clade during the Early Cretaceous, and Xenotyphlopidae and Typhlopidae likely diverged from one another during the Late Cretaceous. [9]

Scolecophidians are believed to have originated on Gondwana, with anomalepidids and leptotyphlopids evolving in west Gondwana (South America and Africa) and the Typhlopoidea (typhlopids, gerrhopilids, and xenotyphlopids) on east Gondwana, initially on the combined India/Madagascar land mass, during the Mesozoic. [9] Typhlopids, initially isolated on Madagascar, then dispersed to Africa and Eurasia. South American typhlopids appear to have evolved from African typhlopids that rafted across the Atlantic about 60 million years ago; they, in turn, dispersed to the Caribbean about 33 million years ago. [9] Similarly, typhlopids appear to have reached Australia from Southeast Asia or Indonesia about 28 million years ago. [9] Meanwhile, the gerrhopilids, isolated on Insular India, underwent a radiation throughout tropical Asia following the collision of India with Asia, while the xenotyphlopids remained isolated on Madagascar. [11]

The Malagasy typhlopoids ( Madatyphlops in Typhlopidae and Xenotyphlops in Xenotyphlopidae) are among the only extant terrestrial vertebrates on Madagascar whose isolation occurred due to vicariance from the Cretaceous breakup of Gondwana. The only other terrestrial vertebrate on Madagascar that shares this evolutionary history is the Madagascan big-headed turtle (Erymnochelys madagascariensis); all other Malagasy land vertebrates dispersed from the mainland to an already-isolated Madagascar from the latest Cretaceous to the present. [11]

Fossil record

Illustration of Boipeba, the earliest known fossil blind snake Cobra-cega.jpg
Illustration of Boipeba , the earliest known fossil blind snake

The extinct fossil species Boipeba tayasuensis from the Late Cretaceous of Brazil was described in 2020, marking the earliest fossil record of Scolecophidia. It was a sister group to Typhlopoidea and was over 1 meter in length, making it much larger than most modern blindsnakes, with only Afrotyphlops schlegelii and Afrotyphlops mucruso rivaling it in size. Prior to this, the earliest scolecophidian fossils were only known from the Paleocene of Morocco and the Eocene of Europe. [12]

Possible Typhopid skin has been identified in Dominican amber. [13]

Phylogeny

This phylogeny combines the ones recovered by Vidal et al. in 2010 and Fachini et al. in 2020. [9] [12]

Scolecophidia

Description

The common name of Scolecophidia, blind snakes, is based on their shared characteristic of reduced eyes that are located under their head scales. [14] These head scales are found in all snakes and are referred to as spectacles, but within this infraorder, they are opaque, resulting in decreased visual capabilities. [3] Reduced eyes of the Scolecophidia have been attributed to evolutionary origins of snakes, which are hypothesized to have arisen from fossorial ancestors, causing a loss of genes related to eyesight that later evolved again in higher snakes to be similar to other vertebrates due to convergent evolution. [14] Newer research shows that seven of the 12 genes associated with bright-light vision in most snakes and lizards are not present in this infraorder, and the common ancestor of all snakes had better eyesight. [15] Other shared characteristics include an absent left oviduct in four of the five families, aside from the Anomalepididae, which have a well developed yet reduced left oviduct. [3] Aside from this, these snakes range in length from 10 to 100 cm (4 to 39 in). Their typical body shapes include slender, cylindrical bodies and small, narrow heads. [14] All these families either lack or have a vestigial left lung and lack cranial infrared receptors. [3]

Behavior

The main shared characteristic found across all Scolecophidia is a fossorial nature, either living underground or within logs and leaf litter. [3] Aside from this, thus far the reproduction remains understudied with all Scolecophidia studied thus far being noted to be oviparous, [3] with elongate eggs noted in both leptotyphlopids and typhlopids. [16] Foraging behaviors vary across families, but all feed on invertebrates. Some of their main food sources include ant or termite eggs, which are tracked down by following chemical cues left by these invertebrates to create trails. [16] Tricheilostomata macrolepis has been seen climbing up trees and waving its head side to side vertically to detect chemical cues in the air to locate insect nests. [3] In a study on the Leptotyphlopidae, some species were found to specialize in eating only termites or ants; some rely on binge feeding patterns, while others do not. [3] While these snakes are often difficult to locate due to their burrowing habits, they are more often seen above ground after rain due to flooding that occurs in burrows. The ancestral nature of the Scolecophidia has resulted in the use of these organisms as models for evolutionary studies in Serpentes to better understand evolution of reproduction, morphology, and feeding habits. [16]

Related Research Articles

<span class="mw-page-title-main">Dibamidae</span> Family of lizards

Dibamidae or blind skinks is a family of lizards characterized by their elongated cylindrical body and an apparent lack of limbs. Female dibamids are entirely limbless and the males retain small flap-like hind limbs, which they use to grip their partner during mating. They have a rigidly fused skull, lack pterygoid teeth and external ears. Their eyes are greatly reduced, and covered with a scale.

<span class="mw-page-title-main">Ophidia</span> Group of squamate reptiles

Ophidia is a group of squamate reptiles including modern snakes and reptiles more closely related to snakes than to other living groups of lizards.

<span class="mw-page-title-main">Typhlopidae</span> Family of snakes

The Typhlopidae are a family of blind snakes. They are found mostly in the tropical regions of Africa, Asia, the Americas, and all mainland Australia and various islands. The rostral scale overhangs the mouth to form a shovel-like burrowing structure. They live underground in burrows, and since they have no use for vision, their eyes are mostly vestigial. They have light-detecting black eye spots, and teeth occur in the upper jaw. Typhlopids do not have dislocatable lower jaw articulations restricting them to prey smaller than their oral aperture. All species in the family Typhlopidae are fossorial and feed on social fossorial invertebrates such as termites and ants. The tracheal lung is present and chambered in all species. One species, the Brahminy's blind snake, is the only unisexual snake, with the entire population being female and reproducing via parthenogenesis. The tail ends with a horn-like scale. Most of these species are oviparous. Currently, 18 genera are recognized containing over 200 species.

<i>Amerotyphlops trinitatus</i> Species of snake

Amerotyphlops trinitatus, known commonly as the Trinidad blindsnake, Trinidad worm snake, and Trinidad burrowing snake, is a harmless blind snake species in the family Typhlopidae. The species is endemic to Trinidad and Tobago. There are no subspecies that are recognized as being valid.

<i>Indotyphlops braminus</i> Species of reptile

Indotyphlops braminus, commonly known as the brahminy blind snake and other names, is a non-venomous blind snake species, found mostly in Africa and Asia, and has been introduced in many other parts of the world. It is a completely fossorial reptile, with habits and appearance similar to an earthworm, for which it is often mistaken, although close examination reveals tiny scales and eyes rather than the annular segments characteristic of a true earthworm. The species is parthenogenetic and all known specimens have been female. The specific name is a Latinized form of the word Brahmin. No subspecies are currently recognized as being valid.

The Andaman worm snake is a species of harmless blind snake in the family Gerrhopilidae. The species is endemic to the Andaman Islands. No subspecies are currently recognized.

Argyrophis oatesii, also known commonly as the Andaman Island worm snake or Oates's blind snake, is a species of harmless snake in the family Typhlopidae. The species is endemic to the Andaman Islands. There are no subspecies that are recognized as being valid.

<span class="mw-page-title-main">Pelvic spur</span> Modified reptilian appendages

Pelvic spurs are external protrusions found around the cloaca in certain superfamilies of snakes belonging to the greater infraorder Alethinophidia. These spurs are made up of the remnants of the femur bone, which is then covered by a corneal spur, or claw-like structure. This femur derives from ancestral hind limbs found in the most recent common ancestor of modern snakes and the other reptiles of the clade Toxicofera, many of which have fully functional front and hind limbs. Due to the fact that the spurs derive from the ancestral state of functional legs, but are no longer functional for locomotion specifically, these structures meet the criteria for being considered vestigial. Nonetheless, uses for the structures have been thoroughly documented. Species that have external spurs have corresponding muscles, neurological structures, and vascularization to allow for independent movement. The spurs are more pronounced and visible in male specimens and have been observed in use during courtship behavior. The spurs are specifically used in the clasping and stimulation of females by males during courtship and mating. In certain species, males will also use their spurs to engage in combat with one another.

Xenotyphlops is a genus of snakes, the only genus of the family Xenotyphlopidae, comprising two species found only in Madagascar. These snakes are also known as the Malagasy blind snake.

Xenotyphlops grandidieri is a species of blind snake in the family Xenotyphlopidae. The species is endemic to Madagascar. There are no subspecies that are recognized as being valid.

<span class="mw-page-title-main">Alethinophidia</span> Clade of snakes

The Alethinophidia are an infraorder of snakes that includes all snakes other than blind snakes and thread snakes. Snakes have long been grouped into families within Alethinophidia based on their morphology, especially that of their teeth. More modern phylogenetic hypotheses using genetic data support the recognition of 19 extant families, although the taxonomy of alethinophidian snakes has long been debated, and ultimately the decision whether to assign a particular clade to a particular Linnaean rank is arbitrary.

<span class="mw-page-title-main">Interior blind snake</span> Species of reptile

Anilios endoterus is commonly known as the interior blind snake. It is one of 42 species of snake in the genus Anilios (Ramphotyphlops) from the Typhlopidae family living in Australia. These snakes appear to be blind, having vestigial eyes that are extremely sensitive to light. It is a cryptic burrowing snake that lives in tunnels underground, living mainly on a diet of ants. They are found in arid and semi-arid desert regions of central Australia and are considered endangered in New South Wales (NSW).

The Angolan giant blind snake or Angolan giant blind-snake, also known as the anomalous beaked snake, is a species of snake in the Typhlopidae family. It is endemic to Angola. Its classification was changed from Rhinotyphlops to Megatyphlops when Rhinotyphlops was found to be polyphyletic. In 2014 Megatyphlops was changed to Afrotyphlops.

Madatyphlops domerguei is a species of snake in the family Typhlopidae. The species is endemic to Madagascar.

Argyrophis klemmeri, also known commonly as Klemmer's blind snake and the Kuala Lumpur worm snake, is a species of Asian snake in the family Typhlopidae.

Schmidt's blind snake is a species of snake in the family Typhlopidae. The species is endemic to Central and Southern Africa.

<i>Afrotyphlops schlegelii</i> Species of snake

Afrotyphlops schlegelii, commonly known as Schlegel's beaked blind snake or Schlegel's giant blind snake, is a species of snake in the family Typhlopidae. The species is endemic to eastern and southern Africa, and bears the distinction of being the world's largest typhlopid. It is harmless to humans and lives exclusively on a diet of termites.

The Gerrhopilidae are a family of blindsnakes that contains at least 16 species in the genus Gerrhopilus, and possibly others as well. These blindsnakes are found in India, Sri Lanka, Nepal, Thailand, the Philippines, Indonesia, and Papua New Guinea.

<i>Boipeba tayasuensis</i> Extinct genus of snakes

Boipeba is an extinct genus of blind snake from the Late Cretaceous (post-Turonian) of Brazil. It contains a single species, Boipeba tayasuensis. The species is known from a single precloacal vertebra from the Adamantina Formation of northwestern São Paulo.

References

  1. 1 2 McDiarmid RW, Campbell JA, Touré TA (1999). Snake Species of the World: A Taxonomic and Geographic Reference, Volume 1. Washington, District of Columbia: Herpetologists' League. 511 pp. ISBN   1-893777-00-6 (series). ISBN   1-893777-01-4 (volume).
  2. 1 2 3 4 5 "Scolecophidia". Integrated Taxonomic Information System . Retrieved 14 August 2007.
  3. 1 2 3 4 5 6 7 8 Vitt, Laurie J.; Caldwell, Janalee P. (2014). Herpetology: An Introductory Biology of Amphibians and Reptiles (Fourth ed.). Academic Press. pp. 597–603. ISBN   978-0-12-386919-7.
  4. ↑ Scolecophidia at Palaeos. Accessed 21 December 2013.
  5. 1 2 Uetz, Peter. "The Reptile Database". The Reptile Database. Retrieved 31 December 2017.
  6. ↑ Miralles, Aurélien; Marin, Julie; Markus, Damin; Herrel, Anthony; Hedges, Blair; Vidal, Nicolas (2018). "Molecular evidence for the paraphyly of Scolecophidia and its evolutionary implications". Journal of Evolutionary Biology. 31 (12): 1782–1793. doi: 10.1111/jeb.13373 . PMID   30193402. S2CID   52174313.
  7. ↑ Bailly, Anatole (1981-01-01). Abrégé du dictionnaire grec français. Paris: Hachette. ISBN   978-2010035289. OCLC   461974285.
  8. ↑ Bailly, Anatole. "Greek-french dictionary online". www.tabularium.be. Retrieved January 7, 2019.
  9. 1 2 3 4 5 6 7 Vidal, Nicolas; et al. (2010). "Blindsnake evolutionary tree reveals long history on Gondwana". Biology Letters. 6 (4): 558–561, page 560. doi:10.1098/rsbl.2010.0220. PMC   2936224 . PMID   20356885.
  10. ↑ Vitt, Laurie J.; Caldwell, Janalee P. (2013). Herpetology: An Introductory Biology of Amphibians and Reptiles. Academic Press. p. 600. ISBN   9780123869203.
  11. 1 2 Ali, Jason R.; Hedges, S. Blair (2023-05-04). "The colonisation of Madagascar by land‐bound vertebrates". Biological Reviews. doi:10.1111/brv.12966. ISSN   1464-7931.
  12. 1 2 Thiago Schineider Fachini; Silvio Onary; Alessandro Palci; Michael S.Y. Lee; Mario Bronzati; Annie Schmaltz Hsiou (2020). "Cretaceous blindsnake from Brazil fills major gap in snake evolution". iScience. 23 (12): Article 101834. doi: 10.1016/j.isci.2020.101834 . PMC   7718481 . PMID   33305189.
  13. ↑ Poinar, George O.; Poinar, Roberta (1999). The Amber Forest: A Reconstruction of a Vanished World. Princeton University Press. ISBN   978-0-691-05728-6.
  14. 1 2 3 Simões, B. F.; et al. (2015). "Visual system evolution and the nature of the ancestral snake". Journal of Evolutionary Biology. 28 (7): 1309–1320. doi: 10.1111/jeb.12663 . PMID   26012745. S2CID   24013194.
  15. ↑ Burrowing snakes have far worse eyesight than their ancestors
  16. 1 2 3 Webb, J.K.; Shine, R.; Branch, W.R.; Harlow, P.S. (2000). "Life‐history strategies in basal snakes: reproduction and dietary habits of the African thread snake Leptotyphlops scutifrons (Serpentes: Leptotyphlopidae)". Journal of Zoology. 250 (3): 321–327. doi:10.1017/s0952836900003058.
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