Which can be excluded due to the absence of fossil records?
the body of a jellyfish
a dinosaur's backbone
the shell of a crab
the shell of a snail
the body of a jellyfish
The body of a jellyfish can be excluded due to the absence of fossil records.
To determine which of these can be excluded due to the absence of fossil records, we need to understand how fossils form and what types of organisms are more likely to leave behind fossils.
Fossils are formed when the remains or traces of organisms are preserved in rocks over geological time. The process typically involves the burial and gradual mineralization of the organism's hard parts, such as bones, shells, or teeth. Soft tissues, like the body of a jellyfish, are usually not well-preserved and rarely fossilize.
Now, let's analyze each option based on their likelihood of leaving fossil records:
1. Body of a jellyfish: As mentioned earlier, soft-bodied organisms like jellyfish are less likely to fossilize. Since the body of a jellyfish does not have hard parts, it would be unlikely to be preserved as a fossil. Therefore, we can exclude the body of a jellyfish due to the absence of fossil records.
2. Dinosaur's backbone: Dinosaurs, including their bones, have been extensively studied and documented in the fossil record. Their skeletons are commonly found in various types of sediments, indicating that dinosaur bones can fossilize well. So, the presence of a dinosaur's backbone can be supported by fossil records.
3. Shell of a crab: Crustaceans, such as crabs, have hard exoskeletons that can fossilize when conditions are favorable. Fossilized crab shells have been discovered in many locations around the world, indicating that they can be preserved in the fossil record. Therefore, the shell of a crab is likely to have fossil records to support its existence.
4. Shell of a snail: Snails also have hard shells made of calcium carbonate, which can withstand the fossilization process under the right conditions. Fossilized snail shells, often found in sedimentary rocks, have provided valuable information about ancient environments. Consequently, the shell of a snail is another example that can be supported by fossil records.
In conclusion, while the body of a jellyfish can be excluded due to the absence of fossil records, the backbone of a dinosaur, the shell of a crab, and the shell of a snail are all likely to have fossil records that support their existence.