a. Desert organisms are typically rare in the fossil record because deserts are environments that are not conducive to fossilization. Deserts are characterized by harsh conditions, such as extreme temperatures, high winds, and low moisture levels, which make it difficult for organisms to be preserved after they die. In addition, many desert organisms are small, with delicate body structures that are easily decomposed or destroyed before they can be fossilized. As a result, the fossil record of desert organisms is often incomplete or nonexistent.
b. Flowers are also typically rare in the fossil record because they have delicate, soft tissues that are not easily preserved. Flowers are reproductive structures that are composed of delicate petals, stamens, and pistils, which are made up of soft tissues that quickly decay after an organism dies. In addition, flowers are typically small and fragile, making them susceptible to damage and destruction during the fossilization process. As a result, the fossil record of flowers is often incomplete or nonexistent, with only a few rare exceptions where exceptional preservation has occurred, such as in amber deposits.