Field work flash cards

Factors Preventing Excavation of Dinosaur Fossils

• Perfectly preserved dinosaur bones or skeletons can become undetectable or inaccessible due to various circumstances.

  • May lie in remote locations, exposed but not discovered.

  • Subject to disintegration from modern weathering processes.

  • Geography can hinder excavation, e.g., steep cliffs or buried under city infrastructure.

Case Study: Discovery in Edmonton

• A sewer maintenance crew stumbled upon several dinosaur bones deep underground in a built-up area.

• Bones could not be excavated further due to accessibility issues.

Natural Predation and Environmental Conditions

• Predators may consume dinosaur remains before burial, leading to the loss of potential fossils.

• Environmental factors like location (forests, mountains, deserts) affect preservation likelihood.

• If a carcass remains in an area without burial, the bones disintegrate over time.

Dinosaur Provincial Park

• Home to millions of exposed dinosaur bones, although many are isolated and fragmentary.

  • Isolated vertebrae, rib bits, and fragments provide limited information.

  • Weathering and predation beforehand complicate identification.

• Notable Finds:

  • Tyrannosaur tooth (Gorgosaurus) - sheds teeth throughout life similar to sharks.

Fossil Collection Process

• Fossils intended for collection are meticulously recorded:

  • Each specimen includes a unique field number, identification, geological age, and GPS location.

• GPS provides precise latitude, longitude, and altitude data for specimen location.

Danix Site Discoveries

• Danix site near Edmonton yielded many dinosaur bones, specifically from the Edmontosaurus.

  • Bone beds consist of many individuals, often found in river channels where sediment accumulates.

  • Significant bone beds provide insight into community structure and behavior.

Rock Types and Fossil Preservation

• Types of rocks encountered:

  • Mudstone, Siltstone, Shale - Indicates quiet water environments, excellent for fossil preservation.

  • Sandstone - Coarser grained, suggests faster environments, potentially rapid burial.

• Distinction based on sedimentary conditions affecting preservation quality.

Quarry Excavation Techniques

• Two phases in quarry excavation were mentioned:

  1. Discovery of skeletons with initial excavation efforts.

  2. Return for full excavation when crucial parts, such as skulls, were found in prior collections.

• Historical context includes techniques from previous collectors.

Excavation Tools and Methods

• Modern techniques involve:

  • Use of geological hammers, chisels for softer rocks; dental picks and brushes for precision near bones.

  • Protective casing of fossils using plaster and burlap akin to medical casts.

• Rock difficulty varies globally, with some locations requiring heavy machinery.

Laboratory Analysis and Reconstruction

• At the University of Alberta, teams work on:

  • Removing matrix rock, repairing fractures with adhesives.

  • Detailed mapping of fossils for identification and research purposes.

• Each bone is cataloged and stored for future study or display.

Edmontosaurus and Albertosaurus Context

• Danix bone bed primarily consists of Edmontosaurus remains, demonstrating diversity among ages and sizes.

• Analysis includes:

  • Counting skeletal elements to assess individual species represented (unique elements like left femur).

  • Evidence of predation, such as bite marks and bone fractures indicating scavenging behavior from Albertosaurus.

Interpretation of Bone Beds

• Bone positioning reveals environmental conditions of burial:

  • Orientation discrepancies indicate a quiet water setting, different from faster flowing environments.

• Ongoing research seeks to determine the circumstances leading to the mass death of the dinosaurs.

  • Clues like drought, disease, or forest fire are minor considerations being investigated.

Conclusion

• Key learning points include:

  • Techniques for fossil recovery and excavation.

  • Importance of geological context in understanding dinosaur fossils.

  • Recording systems and how discoveries contribute to scientific knowledge.

• Future learning: focus on dinosaur adaptations and feeding behaviors.