Pan Gnathostomata 2 Flashcards
Basic Anatomy of Fins
Basal element, radials, and fin rays
Internal to external
What is the basal element?
Mesoderm, cartilage, mineralized cartilages, perichondral and endochondral ossification
What are radials?
Mesoderm, cartilage, chondral bone, different segmentation patterns
What are fin rays?
Ledipdotrichia? Are dermal
What are the “internal” fin structures of paired fins?
Girdles! Except radials
Pectoral Girdle Information: Gnathostome Crown
Plesiomorphic
- LPM, cartilage/endochondral bone
Gnathostome Crown
- + dermal components & including cranial neural crest
Attachment to rest of axial skeleton highly variable across Gnathostomata
Pelvic Skeleton Information regarding Gnathostomes
LPM, no membraneous component, plesiomorphic tognathostomes
Early W3 Gastrulation regarding the mouth
oropharyngeal membrane
- retains bilaminar
- ectoderm top, endoderm bottom
Future mouth!
Emergence Of Neck
Pharynx elongates!
Differential growth
Between coelom & 1st aortic arch
Source of cells = neural crest
Segmentation of Neck
1,2,3,4,6 pharyngeal arches (outside) and pouches(insides)
Pharyngeal septa: ectoderm external and endoderm internally
Cranial Nerves per Arch
What Cranial Nerves are to Each Pouch
1st arch: CV/trigeminal
2nd arch: C XII
3rd arch: C IX
4th arch: C X (superior laryngeal)
6th arch: C X (inferior laryngea)
Even more Gnathostomata Synaomorphies
1) Splanchnocranium
- Skeleton of pharynx
- Mandibular Arch (PA 1)
– partially separated by stomodeum, neural crest
– Palatoquadrate (PTQ) upper and Meckel’s Cartilage is lower
2) Hyoid Arch (PA 2)
- C VII
-hyomandibular, ceratohyal
Jaw suspensions
Autostylic, Amphystylic, Hyostylic, Holostylic
Autostylic Jaw Suspension
PTQ attached, not fused
Arch II free
Amphystylic jaw Suspension
PTQ attached, not fused
Jaw supported by both hyomadibular and ceratohyal
Think amphibian=both ladna nd water= both hyomadibular and ceratohyal
