A chicken is a sexually reproducing organism that undergoes meiosis to produce gametes. Meiosis is a type of cell division that involves the production of daughter cells (gametes) that have their chromosomal number reduced by half.
Hence, if the somatic or body cell of the chicken being ingested by Amanda contains 78 chromosomes, it will undergo meiosis to produce a sperm or egg that has 39 chromosomes i.e. reduced from diploid (2n) to haploid (n).
Somatic or body cells are diploid and are denoted by 2n number of chromosomes. During meiosis, specifically after meiosis I in cell division, the chromosome number is reduced to half the number of that of the somatic cell, and is referred to as haploid, which is denoted by n number of chromosomes.
Therefore, if the somatic cell of the bird has 78 chromosomes, the sex cell (unfertilized egg or sperm) would contain half of the number of chromosomes of the somatic cell = 39 chromosomes.
"Plate movement is thought to be driven by a combination of the motion of the seafloor away from the spreading ridge (due to variations in topography and density of the crust, which result in differences in gravitational forces) and drag, with downward suction, at the subduction zones."