In this article we will discuss about the structure of different vertebrata.
Skull:
1. Presence of cranium, sensory capsules, foramen magnum and jaws.
Ready identification:
Identification: Skull Bufo, Rana:
Subphylum Vertebrata:
1. Cranium bony or cartilagenous and encloses a cavity.
2. Cranium constituted by three rings— occipital, parietal and frontal.
3. Sense capsules—olfactory, optic and otic.
4. Foramina for cranial nerves and blood vessels present.
5. Foramen magnum at the posterior end and bounded by occipital condyles.
6. Presence of jaws in the majority.
Class — Amphibia:
1. Ossification incomplete.
2. Cranium bony.
3. Skull sub-triangular and low.
4. Occipital condyles two.
5. No supra or basioccipitals.
6. Quadrate and jugal fused.
7. Frontal and parietal fused.
8. An unpaired sphenethmoid present.
9. Para-sphenoid dagger-shaped, located on the floor and the ends of the handle reach the prootics.
10. Squamosal hammer-shaped.
1. Bufo sp. (Toad):
(Figs. 42.1, 42.2A, B)
1. Bones rough.
2. Nasals and frontoparietals wide.
3. Absence of teeth.
4. Upper jaw parabolic.
5. Mandible consists of two rami, joined anteriorly by mentomeckelian cartilage (42.2C).
6. Elements of ramus—an outer, dorsal dentary and an inner, ventral angulosplenial.
7. Presence of articular surface on angulosplenial for articulation with quadrate.
2. Rana sp. (Frog):
(Figs. 42.2A’, B’)
1. Bones smooth.
2. Nasals and frontoparietals narrow.
3. Presence of acrodont teeth on vomer, premaxilla and maxilla.
4. Upper jaw conical.
(Mandible (Fig. 42.2C’) same as in Bufo sp)
Trionyx, Uromestix, Calotes, Varanus:
3. Trionyx sp.:
(Figs. 42.3A-C)
Subphylum — Vertebrata:
Class — Reptilia:
1. Well ossified and heavy.
2. Cranium small.
3. Single occipital condyle.
4. Basisphenoid and basioccipital large.
5. Para-sphenoid narrow and elongated.
6. Temporal vacuities may or may not be present.
7. Conical, homodont teeth (except Chelonia).
Subclass — Anapsida:
1. Articulation along sutures firm and the skull is a compact structure.
2. Complete bony ring in the temporal region.
3. No temporal vacuities.
Order — Chelonia:
1. Occipital region trilobed.
2. Supraoccipital crest strongly developed.
3. Quadrate immovably fixed.
4. Lower temporal arch composed of jugal and quadratojugal.
5. Alisphenoid absent.
6. Nasals flat, triangular and fused in the middle.
7. Nasal opening single.
8. Jaw with a horny sheath.
Trionyx sp.:
(Fig. 42.3)
1. Squamosal with backwardly projecting curved process.
2. Two rami of the mandible united anteriorly.
3. Elements of ramus—dentary, angular, supra-angular, coronoid, splenial and articular (Fig. 42.3C).
4. Articular bears a facet at the base for articulation with quadrate.
5. Devoid of teeth, jaw covered with a horny sheath.
Uromastix sp.:
Subphylum — Vertebrata
Class — Reptilia
Subclass — Lepidosauria:
1. Presence of two temporal vacuities, reduced in some.
2. Temporal arches two—supra and infra-temporal.
3. Postorbital and squamosal usually meet posteriorly.
Order — Squamata:
1. Temporal vacuity one.
2. Quadrate movably articulated.
3. Nasal apertures two and separate,
Suborder — Lacertilia:
1. Premaxillae, maxillae and pterygoid fixed.
2. Inter-orbital septum thin and cartilaginous.
3. Teeth present in maxillae and premaxillae.
4. Uromastix sp.:
(Figs. 42.4 A-C)
1. Cranial cavity small.
2. Orbit closed.
3. Presence of a pineal foramen at the posterior end of the frontal.
4. Teeth acrodont, homodont and present in premaxillae and maxillae.
5. A ramus of mandible consists of six bones—dentary, angular, supra-angular, coronoid, splenial and articular (Fig. 42.4C).
6. Articular bears a facet at the base for articulation with quadrate.
7. Teeth present in dentary.
5. Calotes sp. (Garden lizard):
(Figs. 42.5A, B)
1. Trans palatine in front of basioccipital.
2. Para sphenoid reduced.
3. Parietals enclose a median hole, parietal foramen, at the junctions of frontals and parietals.
4. Pre-frontals in front of frontals and post-frontals behind the orbit.
5. Mandible (Fig. 42.5C) same as in Uromastix; points 5 to 7.
6. Varanus sp. (Figs. 42.5A’, B’):
Subphylum — Vertebrata
Class — Reptilia
Subclass — Lepidosauria
Order — Squamata
Suborder — Lacertilia
1. Presence of basioccipital, exoccipital and supraoccipital.
2. Basisphenoid large.
3. Parietals united and parietal foramen at the middle.
4. Post-temporal arch incomplete.
5. Presence of exopterygoid and epipterygoid.
6. Nostrils far back in position.
7. Teeth acrodont, homodont polyphyodont and present in premaxillae and maxillae.
8. Articular of the mandible bears a cartilage at the base for articulation with quadrate (Fig. 42.5C’).
(Rest of the characters of the mandible same as in Uromastix; points 5 and 7.)
7. Snakes:
(Fig. 42.6)
Subphylum — Vertebrata
Class — Reptilia
Subclass — Lepidosauria
Order — Squamata
Suborder — Ophidia
1. Cranial cavity long.
2. Quadrate and squamosal immovable.
3. Basioccipital continues forward as an ossified rostrum.
4. The nasal region—maxillae, palatine and pterygoid movable.
5. No inter-orbital septum.
6. Premaxillae small, fused or even absent.
7. Recurved teeth present in maxillae, palatine and pterygoid.
8. Rami of the mandible united by an elastic ligament.
9. Recurved teeth present on dentary.
(Rest of the characters of the mandible same as in Uromastix sp. points 5 and 6).
7A. Poisonous snake:
(Fig. 42.6A)
1. Maxillary teeth modified to poison fangs.
2. Fangs large, curved and grooved or hollow.
3. Premaxillae fused or absent.
7B. Nonpoisonous snake:
(Fig. 42.6B)
1. Poison fangs absent.
2. Maxillary teeth similar to those in-palatine and pterygoid.
3. Premaxillae small and fused.
Columba, Gallus, Psittacula, Anas:
Columba sp. (Pigeon):
Subphylum — Vertebrata
Class — Aves:
1. Cranium round.
2. Skull bones light, pneumatic and smooth.
3. Most of the bones fused intimately and sutures lacking.
4. Single occipital condyle formed by basioccipital.
5. Foramen magnum relatively anterior and ventral in position.
6. Quadrate triradiate and movably articulated with pterygoid and squamosal.
7. Base of the skull strengthened by the union of parasphenoids.
8. Vertical inter-orbital septum formed by the union of parasphenoids.
9. Orbit large.
10. Olfactory capsule cartilagenous.
11. Premaxillae extend forward to form beak.
12. Rami of the mandible fused anteriorly (Figs. 42.8C,C’).
13. Each ramus consists of dentary, splenial, supra-angular, angular and articular.
14. Articular bears a process for articulation with quadrate and further backwards bear two articular processes, outer and inner.
Subclass — Neornithes:
1. Vomer much reduced or absent.
2. Palatines and pterygoids shifted inward and lie against the rostrum.
3. Teeth absent in most cases.
Superorder Neognathae:
1. Slender vomer imperfectly separates palatines or absent.
2. Palatines extend posteriorly and in contact with the base of the cranium.
3. Palatine movably articulated with pterygoid.
4. Teeth absent.
8. Columba sp. (Pigeon):
(Figs. 42.8A, B)
1. Vomer absent.
2. Beak pointed, almost straight.
9. Callus sp. (Fowl):
(Figs. 42.8A’, B’)
1. Vomer median and slender.
2. Beak strongly built, narrow and arched.
10. Psittacula sp. (Parrot; Parakeet):
(Fig. 42.9)
1. Presence of true craniofacial hinge between upper beak and skull.
2. Beak strong, broad, narrow and hooked anteriorly.
11. Anas sp. (Duck):
(Fig. 42.10)
1. Absence of craniofacial hinge between upper beak and skull.
2. Beak flat, broad and anterior end rounded.
Dromaeognathous Skull (Ratites, Tinamus, etc.):
12. Apteryx sp. (kiwi):
(Fig. 42.11)
1. Vomer long, flat, interposed between palatines and pterygoids on one hand and the rostrum of the basisphenoid on the other.
2. Palatines not articulated with the rostrum.
3. Maxillopalatine processes small and do not unite with one another or with vomer.
13. Schizognathous Skull (Callus, Columba sp., etc.):
(Fig. 42.8A’, B’]
1. Vomer small and pointed in front (absent in Columba).
2. Palatines articulate posteriorly with the rostrum.
3. Maxillopalatines do not unite with one another.
14. Aegithognathous Skull (Corvus sp.):
(Fig. 42.11)
1. Vomer broad and truncate in front.
2. Maxillopalatines well developed but not united with one another.
3. Rostrum well developed and articulates with palatines.
15. Desmognathous Skull [Duck, (Anas) Parakeet, etc.]:
1. Vomer small.
2. Maxillopalatines fused in the middle line, forming a spongy palate hiding vomer.
Didelphis, Macropus:
Subphylum — Vertebrata:
Class — Mammalia:
1. Cranium large.
2. Bones firmly united and sutures persistent.
3. Occipital condyles two.
4. Tympanic bulla two.
5. A bony palate formed by maxillae and palatines.
6. Presence of alisphenoid and lachrymal.
7. Quadrate absent.
8. Orbits well separated.
9. Nasal chambers separated by a cribriform plate.
10. Teeth thecodont and heterodont and present in premaxilla and maxilla.
11. Each ramus of the mandible consists of a single bone, dentary.
12. Posterior end of dentary bears three processes—coronoid, condylar and angular and an ascending process for articulation with squamosal.
13. Mandibular teeth thecodont and heterodont.
Subclass — Theria:
1. Jugal participates in the formation of glenoid fossa.
2. Tympanic bulla partly formed by alisphenoid.
3. Orbital and temporal fossae confluent.
4. Zygomatic arch complete.
5. Pterygoid small.
6. Palate fenestrated.
Order — Marsupialia:
1. Incisors unequal in two jaws, more than three on each side in the upper jaw.
16. Didelphis sp. (Opposum):
1. Snout, elongated.
2. Supra-occipitals form a sharp crest.
3. Occipito-parietal crest well developed.
17. Macropus sp. (Kangaroo):
(Figs. 42.13A, B)
1. Premolar long and molariform.
2. Canine absent.
3. Diastema present.
4. Dental formula 
18. Cavia sp. (Guinea pig):
(Fig. 42.14A-C)
Subphylum — Vertebrata
Class — Mammalia
Subclass — Theria
Infraclass — Eutheria:
1. Brain case large.
2. Bony palate solid.
3. Tympanic bone ring-like and forms a true tympanic bulla.
4. Alisphenoid not associated with bulla.
5. Jugal does not take part in the formation of glenoid cavity.
6. Para-sphenoid and orbitosphenoid united.
7. Bulla perforated by carotid canal.
8. Angle of the mandible not inflected.
Order — Rodentia:
1. Skull small.
2. Premaxilla and maxilla long.
3. Zygomatic arch complete.
4. Tympanic bulla large and flask- shaped.
5. Orbit incomplete.
6. Orbital and temporal fossae continuous.
7. Incisors large, sharp and chisel-shaped; enamel absent on the posterior surface.
8. Canine and anterior premolar absent.
9. Diastema present.
Mandible:
(Fig. 42.14C)
1. Symphysis of the lower jaw absent.
2. Angular process of dentary long.
3. One pair of incisors in each jaw.
4. Dental formula 
19. Oryctolagus sp. (Rabbit):
(Fig. 42.14A’-C’)
Subphylum — Vertebrata
Class — Mammalia
Subclass — Theria
Infraclass — Eutheria
Order — Lagomorpha:
1. Skull small.
2. Tympanic bulla large and flask-shaped.
3. Zygoma large.
4. Orbit small, orbital process of frontal well-developed.
5. Squamosal with large glenoid fossa.
6. External auditory meatus prominent.
7. Incisors chisel-shaped, two pairs in the upper jaw and unequal, larger pair in front and smaller pair behind.
8. Enamel of the incisors thick on the anterior and thin on the posterior surface.
9. Canine absent.
10. Diastema present.
11. Premolars three in the upper jaw.
12. Incisors one pair, premolars two pairs.
13. Canines absent.
14. Diastema present.
Mandible:
(Fig. 42.14C’)
1. Anterior epiphysis present.
2. Dentary roughly triangular.
3. Vacuities present in the dentary near angular process.
4. Angular process short.
5. Dental formula 
20. Canis sp. (Dog):
(Fig. 42.15)
Subphylum — Vertebrata
Class — Mammalia
Subclass — Theria
Infraclass — Eutheria
Order — Carnivora:
1. Skull short and high and strongly built.
2. Sagittal and lamboidal crest well developed.
3. Zygomatic arch strongly built.
4. Temporal fossa deep.
5. Glenoid fossa transverse.
6. Tympanic bulla round and large.
7. Canines pointedly sharp.
8. Last premolars modified to carnassial teeth.
9. Condylar process of dentary long and rounded (Fig. 42.1 5C).
10. First lower molars modified to carnassial teeth.
Canis sp.:
1. Partition of tympanic bulla incomplete.
2. Paroccipital process small.
3. Last upper molar absent.
4. Dental formula 
Pteropus, Vespertilio:
Subphylum — Vertebrata
Class — Mammalia
Subclass — Theria
Infraclass — Eutheria
Order — Chiroptera:
1. Bones light and sutures obliterated.
2. Premaxillae small.
3. Nasals narrow and long.
4. Postorbital process of frontal well developed.
5. Orbital and temporal fossae confluent.
6. Zygomatic arch slender and cylindrical.
7. Tympanic bulla ill developed.
8. Molars small.
21. Pteropus sp. (Flying fox): Megachiroptera:
(Fig. 42.16)
1. Muzzle elongated.
2. Postorbital process of the frontal long and bears a foramen.
3. Bony palate narrows backward and continues beyond first molar.
4. Molars devoid of sharp cusps but bear longitudinal grooves.
22. Vespertilio sp. (Bat): Microchiroptera:
(Fig. 42.17)
1. Postorbital process of frontal short.
2. Bony palate narrows down abruptly and does not extend beyond last molar.
3. Molars with sharp cusps and bear transverse grooves.
Lemur, New World Monkey, Old World Monkey:
Subphylum — Vertebrata
Class — Mammalia
Subclass — Theria
Infraclass — Eutheria
Order — Primate:
1. Cranium rounded.
2. Orbital ring complete.
3. Supraorbital ridge prominent.
4. Nasal broad posteriorly.
5. Jugal extends backward.
6. Orbital and temporal fossae confluent.
7. Lachrymal foramen ex-orbital.
8. Foramen magnum broad and directed ventrally.
9. Mandibular symphysis weak.
23. Lemur:
(Fig. 42.18)
Suborder — Lemuroidea:
1. Cranial capacity small.
2. Facial region protruded forward.
3. Jugal extends backward.
4. Nasal broad posteriorly.
5. Orbital and temporal fosae confluent.
6. Procumbent lower incisors.
7. Incisiform lower canines.
Monkeys:
Suborder — Anthropoidea:
1. Cranial capacity moderate.
2. Orbit complete and forwardly directed.
3. Jugal extends a little backward.
4. Nasal narrow posteriorly.
5. Orbital fossa communicates with temporal fossa by a wide fissure.
6. Tympanic bone unites with squamosal.
7. Molars with four cusps.
24. New world monkey (Division Platyrrhina):
(Fig. 42.19)
1. Inter-narial septum broad.
2. Orbitotemporal foramen large.
3. Tympanic bulla well developed.
4. Premolars three.
25. Old world monkey (Division Catarrhina):
(Fig. 42.20)
1. Inter-narial septum narrow.
2. Tympanic bulla ill developed
3. Orbitotemporal foramen small.
4. Premolars two.
26. Human skull:
(Fig. 42.21)
1. Consisting of 22 bones, 14 of the face and 8 of the brain case. Inter-narial septum narrow.
2. No distinct suture between premaxilla and maxilla.
3. Canines do not project beyond other teeth.
4. Nasal bones elevated on the facial plane.
5. Nasal aperture long, oval or pyriform.
6. Dental formula 2.1.2.3/2.1.2.3.