Experiments in the classification of mammalian orders

Summary

Source of content: general zoology lab guide.

Operation method

Experiments in the classification of mammalian orders

Principle

1. to familiarize with the main features of each major mammalian order 2. to learn to use search forms for search identification 3. to recognize common representative and economic species

Materials and Instruments

specimens
Calipers, tape measure, magnifying glass, microscope.

Move

I. Mammal identification terminology and measurements 1. External measurements



1. External measurements
(1) Body length: from the muzzle end of the head to the base of the tail.
(2) Tail length: from the base of the tail to the tip of the tail.
(3) Ear length: from the tip of the ear to where the ear is attached.
(4) Hindfoot length: the full length of the tarsometatarsal portion of the hind limb with the toes attached (not counting the claws).
In addition, it is necessary to identify the sex, weigh the body, and pay attention to the general shape and color of all parts of the body (including the nipples, glands, external genitalia, etc.), as well as the length, thickness and coarseness of the hair.
3. Skull measurements
(1) Cranial total length.
(2) Cranial base length: the length between the occipital condyles and the anterior edge of the skull base bones.
(3) Basal length: the length from the anterior margin of the foramen magnum of the occipital bone to the anterior base of the incisors or the anterior end of the skull base bone.
(4) Interorbital-nasal length; the distance between the posterior margin of the postorbital eminence of the frontal bone and the anterior margin of the ipsilateral nasal bone.
(5) Width of muzzle: the straight line distance between the outer bases of the right and left canines.
(6) Zygomatic width: the horizontal distance between the outer edges of the two cheekbones.
(7) Interorbital width: the distance between the two inner orbital rims.
(8) Cranial width: The maximum width of the cranial part of the brain.
(9) Auditory follicle width: the distance between the two lateral sides of the auditory follicle, located in front of the occipital condyle.
(10) Gap length: the maximum distance between the imaginary maxillary canines.
(11) Upper tooth row length.





A Carnivora skull measurements A-A' orbital-nasal sniffing length; B-B', muzzle width; C-C' posterior head width} D-D' auditory vesicle length, E-E', auditory vesicle width; F-F' zygomatic width I G -G' basal length, H-H' upper dentary length; I-I' interorbital width, B Rabbitiformes Skull Measurements 1. total cranial length; 2. cranial basal length; 3. basal length; 4. dentary gap; 5. upper dentary length; 6. zygomatic width; 7. interorbital width
II. Veterinary Specimen Retrieval and Observation

The subclass True Beasts are higher viviparous species with a true placenta; well-developed brain.

The majority of existing mammals belong to this subclass and are distributed all over the world.

Caveat

1. Take care of laboratory specimens, use them with care and handle them gently.

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