Endoskeleton (exam 2)

Question 1

Analogous Structures

Answer 1

Homologous:
Structures that may have different functions but arose from a common ancestor

Analogous:
Structures that are similar in function but not of same evolutionary origin

Question 2

Homologous Structures

Answer 2

Homologous:
Structures that may have different functions but arose from a common ancestor

Question 3

Hyostylic

Answer 3

1 point of connection
Most sharks and bony fishes

Question 4

Holostylic (autostylic)

Answer 4

Fused to skull

Question 5

Amphistylic

Answer 5

2 points of connection
Ancestral sharks

Question 6

branchial arch

Answer 6

apart of Axial Skeleton
jawless (8) , early jaw (6), modern sharks (5) have this
Branchiocranium is derived from portion of arch

Question 7

Evolutionary changes ending in modern jaws

Answer 7

Jawless:
7 gill slits
8 branchial arches in primitive condition

Early jawed fishes
6 gill slits
6 branchial arches, 2 used for jaws

Modern sharks (most)
5 gill slits + spiracle
5 branchial arches, 3 used for jaws

Question 8

Agnathan skull, gills

Answer 8

Find: Nasal capsul, otic capsule, branchial cartilages

Question 9

Elasmobranch skull:

Answer 9

Find: mandibular arch, hyoid arch, palatoquadrate, Meckel’s cartilage,
hyomandibular, ceratohyal, hyoidean hemibranch, spiracle, basibranchial, branchial arches,
branchiocranium, chondrocranium

Question 10

Bony fish skull

Answer 10

find: dermatocranium, neurocranium, branchiocranium, jaw suspension, hyoid
apparatus, vomer, mandible, supramaxilla, premaxillary/premaxilla and maxillary/maxilla,
dentary, upper jaw, lower jaw, glossohyal (basihyal), pharyngeal teeth, branchiostegals,
hyomandibula, operculum, hyoid apparatus, opercle, preopercle, interopercle, subopercle,
dermal bone, perichondral, endochondral, palatine, quadrate, pharyngeal arches, basibranchial

Question 11

Vertebral column

Answer 11

find: evolution of notochord and spine, axial skeleton, notochord vs. spinal cord,
neural arch elements, amphicelous centrum, neural spine, neural arch, neural canal, abdominal
vertebrae, caudal vertebrae, zygapophysis, intramuscular, hemal (or haemal) arch, hemal spine,
hemal canal, pleural rib

Question 12

Appendicular skeleton:

Answer 12

find: pterygiophores, pectoral girdle, cleithrum, scapular cartilage, scapula,
coracoid, coracoid process, mesocoracoid, basipterygia, pelvic cartilage, pelvic bone, pelvic
girdle, pectoral girdle, soft rays (lepidotrichia), hardened rays, true spines (actinotrichia),
urostyle, hypurals