In biology , a monotypic taxon is a taxonomic group ( taxon ) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera , the term "unispecific" or "monospecific" is sometimes preferred. In botanical nomenclature , a monotypic genus is a genus in the special case where a genus and a single species are simultaneously described.
14-722: Anthropodyptes Anthropornis Archaeospheniscus Crossvallia Delphinornis Duntroonornis Icadyptes Korora Marambiornis Mesetaornis Pachydyptes Palaeeudyptes Platydyptes Anthropornithidae Simpson , 1946 Palaeeudyptinae , the giant penguins , is a paraphyletic subfamily of prehistoric penguins . It includes several genera of medium-sized to very large species, such as Icadyptes salasi , Palaeeudyptes marplesi , Anthropornis nordenskjoeldi , and Pachydyptes ponderosus . Icadyptes reached 1.5 m (4 ft 11 in) in height, while members of Palaeeudyptes and Anthropornis grew even taller and were some of
28-602: A common ancestor ) or paraphyletic (excluding some descendants), these concepts do not apply to monotypic taxa because they contain only a single member. Monotypic taxa are part of a broader challenge in biological classification known as aphyly – situations where evolutionary relationships are poorly supported by evidence. This includes both monotypic groups and cases where traditional groupings are found to be artificial. Understanding how monotypic taxa fit into this bigger picture helps identify areas needing further research. The German lichenologist Robert Lücking suggests that
42-482: A hierarchical system. When taxonomists identify a monotypic taxon, this often reflects uncertainty about its relationships rather than true evolutionary isolation . This uncertainty is evident in many cases across different species. For instance, the diatom Licmophora juergensii is placed in a monotypic genus because scientists have not yet found clear evidence of its relationships to other species. Some taxonomists argue against monotypic taxa because they reduce
56-553: A natural classification. From a cladistic perspective, which focuses on shared derived characteristics to determine evolutionary relationships, the theoretical status of monotypic taxa is complex. Some argue they can only be justified when relationships cannot be resolved through synapomorphies (shared derived characteristics); otherwise, they would necessarily exclude related species and thus be paraphyletic. However, others contend that while most taxonomic groups can be classified as either monophyletic (containing all descendants of
70-402: Is known as "Gregg's Paradox": if a single species is the only member of multiple hierarchical levels (for example, being the only species in its genus, which is the only genus in its family), then each level needs a distinct definition to maintain logical structure. Otherwise, the different taxonomic ranks become effectively identical, which creates problems for organizing biological diversity in
84-407: Is likely that some of the unassigned New Zealand/Antarctican/Australian genera like Delphinornis , Marambiornis , and Mesetaornis do indeed belong into this subfamily, but it is just as probable that others, such as Duntroonornis and Korora , represent another, smaller and possibly somewhat more advanced lineage. The Palaeeudyptinae as originally defined (Simpson, 1946) contained only
98-407: Is particularly associated with island species. Among 25 documented extinct monotypic genera studied, 22 occurred on islands, with flightless animals being particularly vulnerable to human impacts. Just as the term monotypic is used to describe a taxon including only one subdivision, the contained taxon can also be referred to as monotypic within the higher-level taxon, e.g. a genus monotypic within
112-642: The elbow and wrist joints still retained a higher degree of flexibility than the more rigidly lockable structure found in modern genera. The decline and eventual disappearance of this subfamily seem to be connected to increased competition as mammal groups such as cetaceans and pinnipeds became better adapted to a marine lifestyle in the Oligocene and Miocene . The members of this subfamily are known from fossils found in New Zealand , Antarctica , South America , and possibly Australia , dating from
126-674: The Middle or Late Eocene to the Late Oligocene; the Australian Middle Miocene genus Anthropodyptes is also often assigned to this subfamily, as are the remaining genera of primitive penguins except those from Patagonia . Indeed, it was long assumed that all prehistoric penguins that cannot be assigned to extant genera belonged to the Palaeeudyptinae; this view is generally considered obsolete today. It
140-745: The common application of the term monotypic is frequently misleading, "since each taxon by definition contains exactly one type and is hence "monotypic", regardless of the total number of units", and suggests using "monospecific" for a genus with a single species, and "monotaxonomic" for a taxon containing only one unit. Species in monotypic genera tend to be more threatened with extinction than average species. Studies have found this pattern particularly pronounced in amphibians , where about 6.56% of monotypic genera are critically endangered , compared to birds and mammals where around 4.54% and 4.02% of monotypic genera face critical endangerment respectively. Studies have found that extinction of monotypic genera
154-427: The information content of biological classifications. As taxonomists Backlund and Bremer explain in their critique, "'Monotypic' taxa do not provide any information about the relationships of the immediately subordinate taxon". When monotypic taxa are sister to a single larger group, they might be merged into that group; however, when they are sister to multiple other groups, they may need to remain separate to maintain
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#1732773401364168-465: The largest penguins to have ever existed. The massive P. ponderosus may have weighed at least as much as an adult human. They belonged to an evolutionary lineage more primitive than modern penguins. In some taxa at least, the wing, while already having lost the avian feathering , had not yet transformed into the semi-rigid flipper found in modern penguin species: While the ulna and the radius were already flattened to increase propelling capacity,
182-507: The namesake genus, the remainder being placed in the Anthropornithidae. The arrangement followed here is based on the review of Marples (1962) who synonymized the two, with updates to incorporate more current findings. This prehistoric bird article is a stub . You can help Misplaced Pages by expanding it . Anthropodyptes Anthropodyptes is a poorly known monotypic genus of extinct penguin . It contains
196-513: The single species Anthropodyptes gilli , known from a Middle Miocene humerus from Australia . The bone is somewhat similar to those found in members of the New Zealand genus Archaeospheniscus and thus this genus might, like them, belong to the subfamily Palaeeudyptinae . This prehistoric bird article is a stub . You can help Misplaced Pages by expanding it . Monotypic Monotypic taxa present several important theoretical challenges in biological classification . One key issue
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