Taxonomic Key of Skull Modifications
Modifications of the skull in the European genera:
- I. Quadrate articulating with the cranium, supratemporal absent; mandible much shorter than the skull, with coronoid bone; maxillary small, on lower aspect of cranium; pterygoids not extending to quadrate; nasals forming long sutures with the premaxillary, prefrontals, and frontal: Typhlops.
- II. Quadrate suspended from the supratemporal; mandible at least as long as the skull; pterygoids extending to quadrate or mandible.
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- A. Mandible with coronoid bone; nasals in sutural contact with frontals and prefrontals; transverse bone short, not projecting much beyond cranium; maxillary not half as long as mandible, which is not longer than skull (to occiput): Eryx.
- B. No coronoid bone; nasals isolated.
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- 1. Maxillary elongate, not movable vertically.
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- a. Maxillary half as long as mandible.
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- Supratemporal half as long as skull, projecting far beyond cranium; mandible much longer than skull: Tropidonotus.
- Supratemporal not half as long as skull, projecting far beyond cranium; mandible much longer than skull: Zamenis.
- Supratemporal not half as long as skull, projecting but slightly beyond cranium; mandible much longer than skull: Coluber.
- Supratemporal not half as long as skull, not projecting beyond cranium; mandible not longer than skull: Coronella, Contia.
- b. Maxillary not half as long as mandible, which is longer than skull; supratemporal not half as long as skull, projecting beyond cranium.
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- Quadrate longer than supratemporal; maxillary much longer than quadrate, nearly straight in front of prefrontal; a large vacuity between the frontal bones and the basisphenoid: Coelopeltis.
- Quadrate not longer than supratemporal; maxillary little longer than quadrate, strongly curved in front of prefrontal:Macroprotodon
- Quadrate longer than supratemporal; maxillary little longer than quadrate, nearly straight in front of prefrontal: Tarbophis
- 2. Maxillary much abbreviated and erectile; supratemporal not half as long as skull; mandible much longer than skull; basioccipital with a strong process.
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- Maxillary bone solid: Vipera.
- Maxillary bone hollow: Ancistrodon.
- The vertebrae number 130 to 500 - in the European forms 147 (Vipera ursinii) to 330 (Coluber leopardinus).
Read more about this topic: Snake Skeleton, Skull
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