I recently visited the La Brea Tar Pits with my family. We had a great time and learned a lot. One interesting thing we noticed was the ages of the bison found there. Next to some of their jawbones was a sign that said this:
quote:
Migration
Not all the animals lived at Rancho La Brea year round. Some were migratory, traveling in and out of the area. How do scientists know this?
At Rancho La Brea, paleontologists have found fossils of many young bison. They can tell the age of the bison by the number and kind of teeth in the jaw and the amount of wear shown by the teeth. The young bison from the asphalt deposits are either 2 to 4 months old, 14 to 16 months old, or 26 to 30 months old. Each group is thus 12 months (one year) apart. No bison have yet been recovered that are of intermediate ages- 5 to 13 months old or 17 to 25 months old.
These clusters of ages indicate that the bison were present at Rancho La Brea only during a few months of the year. If the calves of extinct bison were born at the same time of the year as modern bison calves, then the bison were present at Rancho La Brea every year during late spring.
My husband and I found it interesting that there were no bison found with ages of 5 to 13 months or with ages of 17 to 25 months. So we did a bit of research. Here's what we discovered:
1. This statement:
quote:
These clusters of ages indicate that the bison were present at Rancho La Brea only during a few months of the year
cannot be true unless all the bison were born on or very near the same day, every year for the 30,000 years represented by the tar pits. If there was any variation (as there is with modern bison) they would've had to move very rapidly through Rancho La Brea staying only a few days at the most. Also they would've had to go through the area during the same few days every year for 30,000 years.
2. This statement:
quote:
If the calves of extinct bison were born at the same time of the year as modern bison calves, then the bison were present at Rancho La Brea every year during late spring.
is false and misleading. Modern bison calves are born mostly in may but can be born any time from mid April through July or August. There were no newborn calves, no one month old calves. If all the calves were born in May, they would've had to go through Rancho La Brea in July, August, or September (mid summer to early fall) even if all the calves were born in April, the earliest they could've traveled through Rancho La Brea would be June . For them to be present at Rancho La Brea during late spring, they would've had to have been born in February or March, which is not when modern bison are born.
3. Their scenario doesn't seem very likely. What seems more likely is that there was some sudden event which killed all those animals, and there were bison ranging from 2-4 months which had been born that year, bison ranging from 14-16 months which had been born last year, and bison ranging from 26-30 months which had been born two years previously.
I would like to point out that I want this to be a very narrow topic. I don't want to be asked to prove how the flood could cause the animals to be trapped in tar. That is not something I have researched. I simply want people to agree with me that a sudden event is more likely if you only consider the ages of the bison babies, and that the scenario given at the museum doesn't adiquately explain what was found.
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