Everything about The Miacids totally explained
The
miacids (Miacidae) were primitive
carnivores which lived during the
Paleocene and
Eocene Epoch about 65 - 33 million years ago. Miacids are thought to have evolved into todays modern carnivorous
mammals of the order
Carnivora.
The miacids were small
marten-like carnivores with long, little bodies, and long tails. Some species were
arboreal, others lived on the
ground. They probably fed on invertebrates,
lizards,
birds and smaller
mammals like
shrews and
opossums. Their
teeth and
skull show that the miacids were less developed than the modern carnivores. They had
Carnivora type
carnassials but lacked fully
ossified auditory bulla (a rounded protrusion). They resembled
Cimolestes, and this suggests that the order Carnivora evolved from a group of
insectivores, related to
Ungulates.
The miacids are divided into two groups: the miacines with a full complement of molars and the viverravines with a reduced number of molars and more specialized carnnassials.
Classification
The Miacidae as traditionally conceived isn't a
monophyletic group: it's a
paraphyletic array of stem
taxa. Traditionally, the Miacidae and the
Viverravidae had been classified in a third, extinct paraphyletic superfamily, the
Miacoidea, from which the direct ancestors of both Carnivora and
Creodonta were thought to have arisen. Today, Carnivora and Miacoidea are grouped together in the crown-clade
Carnivoramorpha, and the Miacoidea are regarded as basal carnivoramorphs. Some species of the genus
Miacis evolved into modern day carnivores of the Order Carnivora, but only the species
Miacis cognitus is a true carnivoran. Thus,
Miacis may be considered the genus of carnivorous mammals that gave rise to all modern Carnivora.
The transition from Miacidae to Carnivora was a general trend in the middle and late Eocene with taxa from both North America and Eurasia involved. The divergence of carnivorans from other miacids is now inferred to be the middle-Eocene (ca. 42 million years ago). Traditionally the Viverravidae (viverravids) had been thought to be the earliest carnivorans with fossil records first appearing in the Paleocene of North America about 60 million years ago, but recent cranial morphology evidence now places them outside the order Carnivora. Some
paleontologists consider the viverravids to be ancestral to the
aeluroid carnivorans (
felids,
hyaenids,
herpestids and
viverrids), but this is now doubted.
Taxonomy
Further Information
Get more info on 'Miacids'.
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