Ediacaran rangeomorphs

Writing assignment #4 In this paper the researchers utilize Pteridinium as a representative model for erniettomorphs. It was chosen due to the fact there was already published research that had specimen measurements. They used Fractofusus to represent rangeomorphs because it is made entirely of rangeomorph frondlets and large numbers of specimens are available. Due to the uncertainty of new module growth structuring they picked the most likely hypothesis to explain it. They used a total of six parameters for Pteridinium which included length, width, wall thickness, hollowness, overlap, and termination. These parameters were used to determine specific surface area to volume (SA/V) ratios for the organism. The control specimen for this study was a modern osmotrophic megabacteria. The SA/V ratios of the ediacaran organisms were compared to the SA/V ratios of these megabacterium to see if osmotrophy was a viable option for them.
Since osmotrophy relies on a large SA/V ratio to insure the proper diffusion throughout the organism, osmotrophy becomes increasingly difficult to achieve with an increase in size. There are three possible ways to maximize the ability to absorb nutrients via osmotrophy and maintain the adequate SA/V ratio. These ways are commonly called Gould’s means. The first mean is through increasing the overall surface while not changing shape such as forming a flat surface. The second way of increasing their ability to absorb nutrients is through creating complications in their structure such as folding, branching, or convolutions. The third, and final way, is by incorporating inactive matter within the organism limiting the actual volume of the organism.
Pteridinium could have utilized two of these means including increasing surface area and incorporating inorganic matter or space within the organism. By creating pockets within the organism, Pteridinium could have increased its size without decreasing any available surface area. This increase