Floating Saltation

marine-deposited dinosaur remains, mainly the distal parts of the animals are preserved (those parts that would have been dangling in the water) and some of these bones exhibit the distinctive toothmarks (or teeth) of their shark or marine crocodile contemporaries.

Whether scavenging happened on the land or at sea, it may mean that body parts of a dinosaur could have been carried far away from the original site of death.

Physical Processes: Water and Wind

Physical processes probably caused the most dramatic changes in locale for a dinosaur's body, moving it from where it died to where it was buried, as illustrated by the bloat-and-float hypothesis. Dinosaur remains buried near the same spot where they died are autochthonous, whereas those that traveled a significant distance from their death site are allochthonous. This section discusses allochthonous remains.

By water or wind, sediments are moved through traction (dragged along a surface) or in suspension (lifted into the fluid medium above a surface). An intermediate form of movement, where a particle "jumps" intermittently, is called saltation. The combination of sediment moved through traction and saltation constitutes the bedload, and suspended particles are the suspended load of a stream (Fig. 7.5). Sediments moved by flowing water show these respective behaviors depending on the competence of the flow, which is a

One important concept to keep in mind is that a dinosaur body (or any of its body parts in a fluvial environment) was subject to the same physics as other sedimentary particles of similar size, shape, or density.

Saltation Traction
FIGURE 7.5 Dinosaur bones demonstrating their behavior as sedimentary particles. Suspension - astralagus; Saltation - scapula; Traction - humerus. Floating sauropod (with an apparent density of less than 1.0 g/cm3) for scale.

measure of the maximum-size particle it can move. Competence in turn is determined by discharge, the volume of water passing a certain point during a certain amount of time, measured through the following formula:

where Q is the discharge, measured in m3/s; A is the cross-sectional area of a stream in m2; and V is the average velocity of the stream in m/s. For example, if the cross-sectional area at a specific place in a stream during the Jurassic was measured as 16.5 m2 and the velocity of the stream at that same place was 4.3 m/s, then the discharge was

In our example, the water (which has mass) was moving, which means that it had momentum, expressed by this formula:

where M is momentum and m is mass. This means that our same example, with its 71 m3 of water converted to kilograms (remember that 1 cm3 of water = 1 g, hence 1000 cm3 = 1000 g; see Table 1.2) and an assumed velocity of 1.0 m/s, had a momentum of

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