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What Makes an Afrothere an Afrothere?
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Mark Harder
What Makes an Afrothere an Afrothere?
@theforestecologist is right, there are very few anatomical synapomorphies (shared derived traits) if any of Afrotheria, and the few there are almost all exhibit homoplasy. But if you want obscure putative anatomical synapomorphies that may not strictly hold:
"
presence of a naviculocalcaneal facet
scattered vomeronasal organ blood vessels, placement of the internal carotid lateral to the anterior pole of pars cochlearis
four allantoic vessel chambers
Presence of a small P3 protocone
presence of well-developed buccal cingula rather than stylar shelves
increase in lumbar vertebra number from 6 to 8 testicondy (intrabdominal testes)"
Are listed by Seiffert 2007 as possibilities-- but only under certain phylogenetic constructions.
@theforestecologist is right, there are very few anatomical synapomorphies (shared derived traits) if any of Afrotheria, and the few there are almost all exhibit homoplasy. But if you want obscure putative anatomical synapomorphies that may not strictly hold:
"presence of a naviculocalcaneal facetscattered vomeronasal organ blood vessels, placement of the internal carotid lateral to the anterior pole of pars cochlearis four allantoic vessel chambers Presence of a small P3 protocone presence of well-developed buccal cingula rather than stylar shelves increase in lumbar vertebra number from 6 to 8 testicondy (intrabdominal testes)"
Are listed by Seiffert 2007 as possibilities-- but only under certain phylogenetic constructions.
The word "Afrothere" comes from Latin Afer (referring to Africa) and Ancient Greek θηρίον (thēríon, meaning “beast”). In other words, "Afrothere" etymologically refers to animals with origins in Africa.
So really, Afrotheria and it's members are referred to based on their origins and not their physical characteristics. In other words, they needn't share morphological characteristics, but rather they all evolved from the same common ancestor from Africa.
Afrotheria is a clade of mammals, the living members of which belong to groups that are either currently living in Africa or [are] of African origin...
They share few anatomical features but many are partly or entirely African in their distribution
These animals are all chordates of the class Mammalia, and therefore do share the common "basal" characteristics shared among all members of these higher taxanomic levels -- for example, a notochord (and backbone), hair, three middle ear bones, mammary glands, etc.
The word "Afrothere" comes from Latin Afer (referring to Africa) and Ancient Greek θηρίον (thēríon, meaning “beast”). In other words, "Afrothere" etymologically refers to animals with origins in Africa.
So really, Afrotheria and it's members are referred to based on their origins and not their physical characteristics. In other words, they needn't share morphological characteristics, but rather they all evolved from the same common ancestor from Africa.
Afrotheria is a clade of mammals, the living members of which belong to groups that are either currently living in Africa or [are] of African origin...
They share few anatomical features but many are partly or entirely African in their distribution
These animals are all chordates of the class Mammalia, and therefore do share the common "basal" characteristics shared among all members of these higher taxanomic levels -- for example, a notochord (and backbone), hair, three middle ear bones, mammary glands, etc.
And what are those "few characteristics"? That last paragraph answers what makes a mammal a mammal, not what makes an afrothere an afrothere. And location is very circumstantial.More
@theforestecologist is right, there are very few anatomical synapomorphies (shared derived traits) if any of Afrotheria, and the few there are almost all exhibit homoplasy. But if you want obscure putative anatomical synapomorphies that may not strictly hold:
" presence of a naviculocalcaneal facet scattered vomeronasal organ blood vessels, placement of the internal carotid lateral to the anterior pole of pars cochlearis four allantoic vessel chambers Presence of a small P3 protocone presence of well-developed buccal cingula rather than stylar shelves increase in lumbar vertebra number from 6 to 8 testicondy (intrabdominal testes)"
Are listed by Seiffert 2007 as possibilities-- but only under certain phylogenetic constructions.
Ref: Seiffert 2007 A new estimate of Afrotherian phylogeny based on simultaneous analysis of genomic, morphological, and fossil evidence. BBC Evolutionary Biology. https://bmcevolbiol.biomedcentral.com/articles/10.1186/1471-2148-7-224
@theforestecologist is right, there are very few anatomical synapomorphies (shared derived traits) if any of Afrotheria, and the few there are almost all exhibit homoplasy. But if you want obscure putative anatomical synapomorphies that may not strictly hold:
"presence of a naviculocalcaneal facetscattered vomeronasal organ blood vessels, placement of the internal carotid lateral to the anterior pole of pars cochlearis four allantoic vessel chambers Presence of a small P3 protocone presence of well-developed buccal cingula rather than stylar shelves increase in lumbar vertebra number from 6 to 8 testicondy (intrabdominal testes)"
Are listed by Seiffert 2007 as possibilities-- but only under certain phylogenetic constructions.
Ref: Seiffert 2007 A new estimate of Afrotherian phylogeny based on simultaneous analysis of genomic, morphological, and fossil evidence. BBC Evolutionary Biology. https://bmcevolbiol.biomedcentral.com/articles/10.1186/1471-2148-7-224
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The word "Afrothere" comes from Latin Afer (referring to Africa) and Ancient Greek θηρίον (thēríon, meaning “beast”). In other words, "Afrothere" etymologically refers to animals with origins in Africa.
So really, Afrotheria and it's members are referred to based on their origins and not their physical characteristics. In other words, they needn't share morphological characteristics, but rather they all evolved from the same common ancestor from Africa.
From the Afrotheria Wikipedia page:
These animals are all chordates of the class Mammalia, and therefore do share the common "basal" characteristics shared among all members of these higher taxanomic levels -- for example, a notochord (and backbone), hair, three middle ear bones, mammary glands, etc.
The word "Afrothere" comes from Latin Afer (referring to Africa) and Ancient Greek θηρίον (thēríon, meaning “beast”). In other words, "Afrothere" etymologically refers to animals with origins in Africa.
So really, Afrotheria and it's members are referred to based on their origins and not their physical characteristics. In other words, they needn't share morphological characteristics, but rather they all evolved from the same common ancestor from Africa.
From the Afrotheria Wikipedia page:
These animals are all chordates of the class Mammalia, and therefore do share the common "basal" characteristics shared among all members of these higher taxanomic levels -- for example, a notochord (and backbone), hair, three middle ear bones, mammary glands, etc.
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