Final answer:
Fossils are used in the reconstruction of phylogenetic trees or cladograms. Through cladistics, scientists identify evolutionary relationships by grouping species into clades based on common ancestry. Fossil evidence found in stratigraphic layers, along with biostratigraphy practices, helps determine the age and ecological context of these organisms.
Step-by-step explanation:
The student’s question refers to the use of fossil records in the reconstruction of phylogenetic trees or cladograms. Cladistics is the method used by scientists to sort organisms into clades, which are groups that descended from a single ancestor. By examining fossils found in various stratigraphic layers, scientists can infer the evolutionary history and relationships between species. This approach can be especially enlightening when studying strata from significant epochs, such as the Carboniferous to Permian periods leading up to the Capitanian extinction event about 260 million years ago. Fossils, such as ammonites, which are commonly used for relative age dating, provide critical evidence for determining the age and characteristics of stratigraphic layers. Furthermore, biostratigraphy, as noted by William Smith in the 19th century, uses fossils for correlating stratigraphic sequences.
When evaluating fossil evidence, characteristics that suggest organisms may be extinct include unique features not seen in contemporary species, and the fossil's presence in geological layers known to predate major extinction events. As for whether specific fossils are found in different formations like the Stevns Klint or Rodvig Formations, this depends on numerous factors, including the age of the formation, the environment it represents, and what is known about species distribution during the time the formation was laid down.
Facies and Biostratigraphy
In biostratigraphy, the presence of certain fossils in a specific stratigraphic layer can serve as indicators of the age and the environmental conditions of that period. The concept of facies also comes into play, asserting that not all stratigraphic units are laterally continuous, which can sometimes complicate correlation between different geographical locations.