When discussing biological classification, it is often stated that a natural taxonomic group should be monophyletic . This means that all species within that group share a single common ancestor, and all descendants of that ancestor belong to the same group. This raises an interesting question: do all living organisms on Earth form a single monophyletic group? Although direct fossil evidence has not yet confirmed this, the theoretical answer is yes. The earliest member of thi

In the article " Stratigraphy — Introduction to Paleontology (Part III) ," several approaches used in identifying rock strata were introduced, including lithostratigraphy, biostratigraphy, and chronostratigraphy. That article also mentioned radiometric dating as the primary method for determining the age of geological strata. Because radiometric dating directly determines a numerical age or time interval, it is referred to as absolute dating . However, radiometric methods are

Let us turn to the topic of evolutionary stasis. Many people have probably encountered popular memes or articles claiming that certain organisms—such as horseshoe crabs or coelacanths—have remained unchanged for hundreds of millions of years. These organisms are sometimes described as examples of evolutionary stasis, a situation in which a lineage appears to undergo little or no evolutionary change for extremely long periods. Fossil records frequently reveal similar patterns:

Phylogenetic Tree（圖片來源：Liang L et al，採用  CC BY 3.0  授權） A phylogenetic tree—also called an evolutionary tree—is a graphical model used to represent the evolutionary relationships among organisms. Its branching structure illustrates how species diverge from common ancestors through evolutionary time. Each branching point represents an evolutionary split, the root of the tree represents the common ancestor of all taxa included in the analysis, and branches closer to the crown c

Carl Linnaeus（圖片來源：Alexander Roslin， CC0 1.0  公共領域） Recently there have been several discussions about changes in scientific names, which reminded me that we have not yet talked about how scientific names are actually used. This article therefore provides a brief introduction to several basic concepts surrounding scientific nomenclature. These ideas may prove useful when similar topics appear in future discussions. To begin with the most fundamental point: scientific names mu

Skull of a dromaeosaur（圖片來源：AS， CC0 1.0  公共領域） Skull of Spinosaurus（圖片來源：AS， CC0 1.0  公共領域） Dinosaurs are among the most frequently studied subjects in paleontology, and their skeletal structures constitute some of the most important fossil evidence available to researchers. Among these skeletal elements, the skull is especially informative because it preserves numerous anatomical features that help scientists interpret feeding behavior, sensory abilities, and evolutionary re

For most of human history, organisms were distinguished primarily by their visible characteristics. Creatures with wings were grouped together, those with fins were placed in another category, and organisms sharing obvious external traits were classified in similar ways. This approach allowed naturalists to sort living things quickly and efficiently according to outward appearance. During the past century, however, the rapid development of evolutionary biology revealed import

Trace Fossils Trace fossils preserve evidence of the activities of organisms in the past, such as footprints, scratch marks, bite marks, feeding traces, burrows, and feces. Most trace fossils are not easily recognized. In the early days of paleontology, many elongated trace fossils were mistakenly interpreted as fossilized seaweeds or worms, and numerous dinosaur footprints were once thought to have been left by giant birds. Modern research on trace fossils largely began with

Origin of Life Based on the ratio of C12 to C13 isotopes, the earliest evidence of life on Earth is currently estimated to date back to about 3.7 billion years ago, during the Eoarchean. However, it is quite possible that life-like substances already existed even earlier during the Hadean eon. How life first emerged has long been an intriguing question, and many hypotheses have been proposed to explain its origin. Some researchers have suggested that the origin of life came f

Morphology, Structure, and Function of Fossils When we look at living organisms today, we often become curious about their outward appearance. Why does a giraffe have such a long neck? Why does a peacock have such long and beautiful tail feathers? Why does a bee have a stinger on its abdomen for defense? With living organisms, we can directly observe and study their morphology, structure, and function. Paleontologists feel the same curiosity when they confront fossils. Some a