Skeleton

Introduction to Dinosaur Anatomy

• Understanding dinosaurs requires knowledge of their skeletons.

• Skeletons provide insight into size and structure of dinosaurs.

Skeleton Composition and Vertebrates

• Dinosaurs and humans share similar skeleton structures; both belong to the category of vertebrates.

• Vertebrates possess a backbone, made up of vertebrae, which are individual bones forming the spine.

  • Example Animals:

  • Vertebrates: Fish, amphibians, reptiles, birds, mammals.

  • Invertebrates: Example is the octopus, which lacks a backbone.

  • Correct Answer to What is a Vertebrate?: B. A backbone

Evolutionary Relationships

• Evolutionary theory explains the relationships among species.

• Visual analogy: A branching tree where primitive ancestors are at the base (trunk) and derived species on the branches.

• Dinosaurs are on the vertebrate branch of this evolutionary tree.

Identifying Vertebrates

• Choices for identification: Octopus, Shark, Human, Snake.

  • Correct answers: Shark, Human, Snake (B, C, D)

  • Characteristics of vertebrates:

  • All vertebrates possess skulls and backbones.

  • Invertebrates lack both.

Evolution of the Vertebrate Skeleton

• Vertebrate skeletons evolved over 300 million years ago.

• Basic bone arrangements are preserved across vertebrates due to a common ancestor.

• Shape and structure of bones indicate adaptation to functional needs.

  • Example Variations: Differences in skull shapes among wolves, mountain lions, and harbor seals.

Understanding the Skull Structure

• The skull consists of multiple bones, not a single one.

• General features related to feeding and senses:

  • Orbits: Openings for the eyes.

  • Nares: Openings for the nasal passage.

  • Fenestrae: Other skull openings, important for vertebrate lineage distinction.

  • Example of Mammalian Skull:

    • Fenestrae: One located behind the orbit (supratemporal) and none in front.

  • Example of Tyrannosaur Skull:

    • Two holes behind the orbit and one in front called the antorbital fenestra.

• Brain Case: Houses the brain and includes nerve openings.

Three-Dimensional Fossil Viewer Activity

• Viewing a Tyrannosaurus skull in 3D provides a basis for learning about anatomical similarities and adaptations.

Backbone and Vertebrae

• Backbone consists of multiple vertebrae:

  • Vertebrae types:

  • Cervical: Neck vertebrae.

  • Dorsal: Back vertebrae.

  • Sacral: Hip vertebrae, fused to hip bones.

  • Caudal: Tail vertebrae.

• Difference in Mammal vs. Dinosaur Ribs:

  • Mammals lack rear ribs; dinosaurs had ribs extending to the pelvis.

  • Presence of Gastralia: Belly ribs unique to dinosaurs, not found in mammals.

Limb Structure and Adaptations

• Arm and leg bones connect to the body via limb girdles.

  • Shoulder Girdle: Composed of the scapula (shoulder blade).

  • Pelvic Girdle: Contains the acetabulum (hip socket).

• Functional Adaptations: Limb structures indicate movement type (walking, running, flying, swimming, jumping).

  • Questioning a dinosaur's capability based on limb structure (e.g., was it fast or a predator?).

Comparison of Human and Dinosaur Limbs

• Major bones in human arms mirror those in Tyrannosaurus arms:

  • Human Arm Bones: Humerus, radius, ulna, and metacarpals.

  • Tyrannosaurus Arm Bones: Humerus in the same position, supporting a different structure (e.g., fewer fingers).

• Evolution demonstrates shared bone structures but differs in specific adaptations like size, shape, and number of digits.

Leg Structure of Tyrannosaurus rex

• Comparable bones present in humans and dinosaurs:

  • Femur: Upper leg bone, same in both species.

  • Lower Leg Bones: Tibia and fibula; fibula frequently broken in common fractures.

• Foot Structure:

  • Five toes present, but not all touch the ground.

  • Inner toe (first) small, supporting toes (second, third, fourth) carry body weight.

  • Fifth toe lost at evolutionary stages but indicated by a splint-like bone.

• Walking behavior: Weight borne on toes, with soles elevated from the ground in most dinosaurs.

Practical Application of Knowledge

• Engage with materials to build a virtual Tyrannosaurus skeleton using acquired anatomical knowledge.

• Steps of assembly:

  • Starting from Hips → Connecting to Cervical Vertebrae → Following to Dorsal Vertebrae → Sacral Vertebrae → Caudal Vertebrae → Finalizing with Ribs and Gastralia.

• Assembly emphasizes anatomical position and function of the dinosaur skeleton.

Conclusion

• Understanding the commonalities in vertebrate anatomy enhances the comprehension of dinosaurs, their adaptations, and evolutionary relationships.