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Caminalcules are a fictive group of animal-like life forms, which were created as a tool for better understanding phylogenetics in real organisms. They were created by Joseph H. Camin (University of Kansas) and consist of 29 living 'species' and 48 fossil forms.
The name of the taxon Caminalcules seems to come from Camin's last name and Antonie van Leeuwenhoek's .
The Caminalcules first appeared in print in the journal Systematic Zoology (now Systematic Biology) in 1983, four years after Camin's death in 1979. Robert R. Sokal published four succeeding papers about them, titled "A Phylogenetic Analysis of the Caminalcules." These papers included the complete set of living and fossil species, as well as their cladogram, which Sokal had received from Camin in 1970.
At a symposium dedicated to Camin, Dr. W. Wayne Moss said that "his collaborative studies on methods and principles of systematics at Kansas in the 1960s resulted in the appearance of that delightful taxon, the Caminalcules", and that "his thoughts helped to launch the infant field of phenetics and cladistics in North America". This quote demonstrates the importance of the Caminalcules for the field of phylogenetics.
Ulrich Wirth introduced also the fictive animal group Didaktozoa in 1993, which was inspired by . According to Ulrich, the Didaktozoa are handier than the Caminalcules and were created in a way that more biologists would agree with, since phenomena such as homologous structures, apomorphy and organ reduction were taken into account in their creation.
The Caminalcules can be used as a tool for evaluating taxonomic methods by virtue of their similarity to data sets of real organisms. Many of their properties, including evolutionary rates, species longevity, homoplasy, parallelism, and other measures for quantifying evolutionary change, are within the range of values that have been observed for real organisms. However, the taxonomic diversity distribution of the Caminalcules differs from the taxonomic diversity distributions of real animals and plants, since it does not follow a hollow curve.
Students are typically asked to construct a phylogenetic tree based on the morphological characteristics of the Caminalcules and taking into account evolutionary principles. In an article in American Biology Teacher, Robert P. Gendron published instructions for a lesson plan in which students are first asked to construct a potential tree based solely on the living Caminalcules, followed by a definitive tree that includes the fossil species.
the University of Miami,Caminalcules. (n.d.). University of Miami. http://ww.bio.miami.edu/dana/107/Caminalcules.pdf Carleton College, and the Turkana Basin Institute. Notably, the United States’ National Park Service also uses the Caminalcules in their lesson plans about evolution.
Using Caminalcules to practice the construction of phylogenetic trees has an advantage over using data sets consisting of real organisms, because it prevents the students’ pre-existing knowledge about the classification of real organisms to influence their reasoning during the exercise. They may only use the given data set and the principles of evolution to come to a solution, which is how real taxonomic problems are solved as well.
There are many other popular phylogenetic exercises that use different sets of ‘organisms’, some of which were inspired by the Caminalcule exercises. Potential alternative data sets include sets of twigs, chocolate bars, Chinese masks, and dragons. Students may also be asked to create their own sets of fictional organisms, which has the additional value of demonstrating macroevolutionary processes. Furthermore, in the case of data sets without a known phylogeny, unlike the case of the Caminalcules, students may find multiple, equally correct solutions. This may demonstrate the fact that taxonomic questions do not always have a single correct response, since the true phylogeny often remains unknown.
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