The answer is "dinosaur hearts" because hearts are soft body parts and do not fossilize well.

Scientists date and categorize fossils to determine when the organisms lived relative to each other. The resulting fossil record tells the story of the past and shows the evolution of forms over millions of years. Fossils are found in rocks and can be formed from hard parts of organisms, such as bones and shells, but soft parts do not form fossils well and fossils of body parts like feathers are much more rare.

One pattern in the fossil record is the presence of forms with transitional characteristics, arranged in sequential stratigraphic order. This means that the fossil record provides evidence for evolution and it shows tiny changes in the structures of organisms as time moved forward.

Major extinction events and natural disasters such as drought or volcanic eruptions can also be seen in the fossil record. Notably the fossil record has large amounts of iridium in the layer titled The 'K–T Boundary' or 'end Cretaceous event', which marks the extinction of the dinosaurs on land. Scientists believe this extinction was the result of a large meteor striking Earth.

The answer is "a mass extinction event in the fossil record caused by a meteor."

Scientists date and categorize fossils to determine when the organisms lived relative to each other. The resulting fossil record tells the story of the past and shows the evolution of forms over millions of years. Fossils are found in rocks and can be formed from hard parts of organisms, such as bones and shells, but soft parts do not form fossils well and fossils of body parts like feathers are much more rare.

One pattern in the fossil record is the presence of forms with transitional characteristics, arranged in sequential stratigraphic order. This means that the fossil record provides evidence for evolution and it shows tiny changes in the structures of organisms as time moved forward.

Major extinction events and natural disasters such as drought or volcanic eruptions can also be seen in the fossil record. Notably the fossil record has large amounts of iridium in the layer titled The 'K–T Boundary' or 'end Cretaceous event', which marks the extinction of the dinosaurs on land. Scientists believe this extinction was the result of a large meteor striking Earth.

The answer is "no human fossils can be found" because prehistoric humans are able to be seen in the fossil record.

Scientists date and categorize fossils to determine when the organisms lived relative to each other. The resulting fossil record tells the story of the past and shows the evolution of forms over millions of years. Fossils are found in rocks and can be formed from hard parts of organisms, such as bones and shells, but soft parts do not form fossils well and fossils of body parts like feathers are much more rare.

One pattern in the fossil record is the presence of forms with transitional characteristics, arranged in sequential stratigraphic order. This means that the fossil record provides evidence for evolution and it shows tiny changes in the structures of organisms as time moved forward. 

Major extinction events and natural disasters such as drought or volcanic eruptions can also be seen in the fossil record. Notably the fossil record has large amounts of iridium in the layer titled The 'K–T Boundary' or 'end Cretaceous event', which marks the extinction of the dinosaurs on land. Scientists believe this extinction was the result of a large meteor striking Earth.

The answer is "There was a body of water there at one point." Due to continental drift and changes to Earth's geography over time, oceans and lakes are in different places today than they were many millions of years ago.

Scientists date and categorize fossils to determine when the organisms lived relative to each other. The resulting fossil record tells the story of the past and shows the evolution of forms over millions of years. Fossils are found in rocks and can be formed from hard parts of organisms, such as bones and shells, but soft parts do not form fossils well and fossils of body parts like feathers are much more rare.

One pattern in the fossil record is the presence of forms with transitional characteristics, arranged in sequential stratigraphic order. This means that the fossil record provides evidence for evolution and it shows tiny changes in the structures of organisms as time moved forward. 

Major extinction events and natural disasters such as drought or volcanic eruptions can also be seen in the fossil record. Notably the fossil record has large amounts of iridium in the layer titled The 'K–T Boundary' or 'end Cretaceous event', which marks the extinction of the dinosaurs on land. Scientists believe this extinction was the result of a large meteor striking Earth.

Scientists date and categorize fossils to determine when the organisms lived relative to each other. The resulting fossil record tells the story of the past and shows the evolution of forms over millions of years. Fossils are found in rocks and can be formed from hard parts of organisms, such as bones and shells, but soft parts do not form fossils well and fossils of body parts like feathers are much more rare.

One pattern in the fossil record is the presence of forms with transitional characteristics, arranged in sequential stratigraphic order. This means that the fossil record provides evidence for evolution and it shows tiny changes in the structures of organisms as time moved forward. 

Major extinction events and natural disasters such as drought or volcanic eruptions can also be seen in the fossil record. Notably the fossil record has large amounts of iridium in the layer titled The 'K–T Boundary' or 'end Cretaceous event', which marks the extinction of the dinosaurs on land. Scientists believe this extinction was the result of a large meteor striking Earth.

The answer is "a mass extinction."

Scientists date and categorize fossils to determine when the organisms lived relative to each other. The resulting fossil record tells the story of the past and shows the evolution of forms over millions of years. Fossils are found in rocks and can be formed from hard parts of organisms, such as bones and shells, but soft parts do not form fossils well and fossils of body parts like feathers are much more rare.

One pattern in the fossil record is the presence of forms with transitional characteristics, arranged in sequential stratigraphic order. This means that the fossil record provides evidence for evolution and it shows tiny changes in the structures of organisms as time moved forward.

Major extinction events and natural disasters such as drought or volcanic eruptions can also be seen in the fossil record. Notably the fossil record has large amounts of iridium in the layer titled The 'K–T Boundary' or 'end Cretaceous event', which marks the extinction of the dinosaurs on land. Scientists believe this extinction was the result of a large meteor striking Earth.

The answer is "sedimentary."

Scientists date and categorize fossils to determine when the organisms lived relative to each other. The resulting fossil record tells the story of the past and shows the evolution of forms over millions of years. Fossils are found in rocks and can be formed from hard parts of organisms, such as bones and shells, but soft parts do not form fossils well and fossils of body parts like feathers are much more rare.

One pattern in the fossil record is the presence of forms with transitional characteristics, arranged in sequential stratigraphic order. This means that the fossil record provides evidence for evolution and it shows tiny changes in the structures of organisms as time moved forward.

Major extinction events and natural disasters such as drought or volcanic eruptions can also be seen in the fossil record. Notably the fossil record has large amounts of iridium in the layer titled The 'K–T Boundary' or 'end Cretaceous event', which marks the extinction of the dinosaurs on land. Scientists believe this extinction was the result of a large meteor striking Earth.

The answer is "The location of Antarctica has shifted north due to tectonic drift and it used to have a warmer climate."

Scientists date and categorize fossils to determine when the organisms lived relative to each other. The resulting fossil record tells the story of the past and shows the evolution of forms over millions of years. Fossils are found in rocks and can be formed from hard parts of organisms, such as bones and shells, but soft parts do not form fossils well and fossils of body parts like feathers are much more rare.

One pattern in the fossil record is the presence of forms with transitional characteristics, arranged in sequential stratigraphic order. This means that the fossil record provides evidence for evolution and it shows tiny changes in the structures of organisms as time moved forward.

Major extinction events and natural disasters such as drought or volcanic eruptions can also be seen in the fossil record. Notably the fossil record has large amounts of iridium in the layer titled The 'K–T Boundary' or 'end Cretaceous event', which marks the extinction of the dinosaurs on land. Scientists believe this extinction was the result of a large meteor striking Earth.

The answer is "the Kaibab Formation" because it is the bottom-most layer of rock and therefore the oldest.

Scientists date and categorize fossils to determine when the organisms lived relative to each other. The resulting fossil record tells the story of the past and shows the evolution of forms over millions of years. Fossils are found in rocks and can be formed from hard parts of organisms, such as bones and shells, but soft parts do not form fossils well and fossils of body parts like feathers are much more rare.

One pattern in the fossil record is the presence of forms with transitional characteristics, arranged in sequential stratigraphic order. This means that the fossil record provides evidence for evolution and it shows tiny changes in the structures of organisms as time moved forward.

Major extinction events and natural disasters such as drought or volcanic eruptions can also be seen in the fossil record. Notably the fossil record has large amounts of iridium in the layer titled The 'K–T Boundary' or 'end Cretaceous event', which marks the extinction of the dinosaurs on land. Scientists believe this extinction was the result of a large meteor striking Earth.

The answer is "Because index fossils only existed for a short time, they can be used as a marker to identify the time period of a rock layer."

Scientists date and categorize fossils to determine when the organisms lived relative to each other. The resulting fossil record tells the story of the past and shows the evolution of forms over millions of years. Fossils are found in rocks and can be formed from hard parts of organisms, such as bones and shells, but soft parts do not form fossils well and fossils of body parts like feathers are much more rare.

One pattern in the fossil record is the presence of forms with transitional characteristics, arranged in sequential stratigraphic order. This means that the fossil record provides evidence for evolution and it shows tiny changes in the structures of organisms as time moved forward.

Major extinction events and natural disasters such as drought or volcanic eruptions can also be seen in the fossil record. Notably the fossil record has large amounts of iridium in the layer titled The 'K–T Boundary' or 'end Cretaceous event', which marks the extinction of the dinosaurs on land. Scientists believe this extinction was the result of a large meteor striking Earth.