<span>The rock layers must have formed at different times because they contain two different biozones.
The rock layer containing the trilobites must have formed before the one containing the ammonites.
The key thing to note here is that the Trilobites only lived from 540 to 248 million years ago. And that the Ammonites were from 245 to 65 million years ago. So there's a 3 million year gap between these 2 different creatures where neither of them existed. So the dig where the trilobites were found has to be at least 3 million years older than the dig where the Ammonites were found. So with that in mind, let's look at the options and see what makes sense.
The rock layers must have formed at the same time because they both contain biozones.
* This is nonsense no matter what dates you're speaking of. In effect it claims that all rocks that indicate life were created at the same time. So this is definitely a bad choice.
The rock layers must have formed at different times because they contain two different biozones.
* This is technically incorrect since it assumes that all biozones represent an unique period of time which is incorrect. However, since the biozones represented by the presence of Trilobites and Ammonites don't overlap, it is true that these these rock layers were formed at different times. I would have preferred if this option said "non overlapping biozones". But on the balance, I'd consider this option to be true, so it should be selected.
The rock layer containing the trilobites must have formed before the one containing the ammonites.
* This is definitely true since the last Trilobite died about 3 million years before the first Ammonite lived. So this is a correct choice.
The rock layer containing the trilobites must have formed after the one containing the ammonites.
* This is the opposite of the previous option. And since the previous option was true, this option must be false. So this is a bad choice.</span>
The choices
are;
a. the
appearance of the first permanent teeth
b. the
appearance of the last permanent teeth
c. rapid
development
d. puberty
The answer
is c. rapid development. Gestational
stage is the time period that a pregnancy needs to exist from conception to
natural birth time. In humans, 40 weeks. Gestation is the carrying of an embryo
or fetus exclusive viviparous animals. It is typical for mammals.
Saudi Arabia is 1 hour ahead of ksa. Saudi Arabia is also extremely close to the equator. Therefore Saudi a Arabia is the answer.
Answer:
C. time for weathering of rock and development of the soil horizons
Explanation:
The primary succession is the initial colonization of a previously existing ecosystem that has been totally destroyed by some disastrous event. During this colonization, the organisms that settle in are ones that do not have any particular requirements for their survival, like the lichens and mosses. As they spread all over the area, they slowly start to influence the rocks on which they have grown, little by little weather them and providing them with organic matter. This gives rise to the first soil horizon, but it is very shallow and the soil is not well formed, so lot of time needs until the soil becomes suitable enough for the secondary succession to occur. When the secondary succession occurs it means that there's soil formed in the area, so new organisms move in, and as they do they replace the ones from the primary succession, slowly forming a new ecosystem and well balanced ecological community.
