Evolutionary anachronism
Evolutionary anachronism is a concept in evolutionary biology named by Connie C. Barlow in her book, "The Ghosts of Evolution" (2000). It refers to attributes of living species that are best explained as a result of having been favorably selected in the past due to coevolution with other biological species that have since become extinct. When this context is removed, the natural attributes appear as unexplained energy investments by the living organism, with no apparent benefit, and perhaps are prejudicial to the continued reproduction of the surviving species. The general theory was formulated by Costa Rican-based American  botanist Daniel Janzen and University of Arizona-based geologist Paul S. Martin (a prominent defender of the overkill hypothesis to explain the Quaternary extinction event) in a "Science" article published in 1982, titled "Neotropical Anachronisms: The fruit the gomphotheres ate." Previously, in 1977, Stanley Temple had proposed a similar idea to explain the decline of the Mauritius endemic tree tambalacoque following the extinction of the iconic dodo. Janzen, Martin and Barlow mainly discussed evolutionary anachronisms in the context of seed dispersal and passive defense strategies exhibited by plants that had evolved alongside disappeared megaherbivores, although some examples apply to animal  species as relict behavior. Evolutionary anachronisms are not the same as vestigiality. Though both concepts refer ultimately to organs that evolved and are no longer present, in the case of anachronisms, the original function of the organ and the capacity of the organism to use it are retained. For example, the present-day absence of gomphotheres eating avocados does not render avocado pulp vestigial, rudimentary or incapable of its original functions in seed nutrition and dispersal (zoochory) if a new suitable ecological partner were to appear. Megafauna dispersal syndrome. Dispersal syndromes are complexes of fruit traits that enable plants to  disperse seeds. The kind of fruits that birds are attracted to are usually small, with only a thin protective skin, and the colors are red or dark shades of blue or purple. Fruits categorized as mammal syndrome are bigger than bird fruits. They possess a tough rind or husk, emit a strong odor when ripe but retain a dull coloration of brown, burnished yellow, orange or remain green, because most mammals have a powerful sense of smell but poor color vision in general, primates being the most notable exception. The megafauna dispersal syndrome refers to those attributes of fruits that  evolved in order to attract megafauna (animals that weigh or weighed more than 44 kilograms) as primary dispersal agents. Since the Holocene extinction, large herbivores have become extinct outside Africa and to a lesser extent Asia, leaving these fruits without a suitable dispersal mechanism in the absence of agriculture. In popular culture. The phenomenon was referenced (though not by name) in the 1259 issue "Bee Orchid" of the online comic strip "xkcd" by Randall Munroe, published on September 2, 2013. In the comic, it is claimed that the orchid "Ophrys apifera" mimics the female of a bee species to attract  males and ensure pollination, but that the bee is extinct and the orchid is doomed to follow, only delaying it by resorting to less effective self-pollination. In reality, only the first part is true: the flower mimics a bee, and reproduces exclusively by self-pollination in northern Europe, but it is pollinated successfully by bees of the genus "Eucera" in the Mediterranean region.