09-09-2018, 04:58 PM
Order Eusymmetrodonta
Mammaliformes "“ Mammalia "“ Theriiformes "“ Holotheria "“ Trechnotheria - Symmetrodonta.
(The Monotremata[i.e. Duck-Billed Platypus & Echidna] are "˜Mammaliformes "“ Mammalia', but not "˜Theriiformes''; Both the Metatheria [which includes the Marsupialia] and the Eutheria [which includes the Placentalia, e.g. ourselves] are "˜Mammaliformes "“ Mammalia "“ Theriiformes "“ Holotheria "“ Trechnotheria "“ Cladotheria - Zatheria'.)
Extinct taxa: Spalacotheriidae, Zhangeotheriidae [both = RL-only, not known in IDU; early Cretaceous to end of Cretaceous]; Chronolestes [also RL only; Palaeocene... inclusion in this group disputed].
Extant taxa: Pseudotalpidae [IDU-only, not known from RL; a few fossils from mid-Miocene, then Pleistocene & modern].
Pseudotalpidae ("˜False Moles')
(c.f. "˜true' Moles, Golden Moles [RL Africa], & Marsupial Moles [RL Australia]).
Geographical Range
IDU "˜South Continent', in most areas where the soils are generally neither too thin nor too water-logged for burrowing.
Lifestyle
All of the extant species are burrowers, whose members spend almost all of the time underground, but depending on species they may either excavate networks of permanent tunnels at varying depths or "swim" through loose soil and sandcloseto the surface.Digging is carried out primarily using the shovel-like forepaws, although the hind-limbs are often also employed for moving loose material aside. Unlike the "˜true' Moles, however, they do not include any semi-aquatic species. Adults of both sexes are solitary, except for the brief periods when females are in breeding condition. The species that create permanent burrows are territorial in nature, but the "˜sand-swimmers' are apparently nomadic and non-territorial instead.
Most species' members feed mainly on earthworms, beetle larvae, and other subterranean invertebrates, but "” especially in the larger species "” they may also take some small vertebrates [most often lizards] as well if &when the opportunity occurs. Some species actually burrow deliberately into the nests of social insects rather than expend the energy that would be needed to seek out enough of those small food-items individually. Prey is always seized using the mouth, rather than with the paws, although the forepaws are used sometimes to push targets into suitable positions for ingestion. There have been confirmed cases of cannibalism in the wild, in at least two species, but this seems to occur only when other food is extremely scarce and [data anecdotal, unconfirmed] only on a same-sex basis.
Skeletal Anatomy
The jaw/skull connection is fully "˜mammalian' in form, with two of the bones on each side that are part of this in other vertebrates moved upwards into the middle ear.
Dental formula = I3 C1 P4 M4.
Their molars are triconodont & symmetrodont but not tribosphenid, without a well-developed talonid, and are acutely triangulated in cross-section.
The postcranial skeletonis also basically modern, although with [short] lumbar ribs still included, but features a "˜primitive' hip-joint that leaves them with a "˜semi-sprawling' posture (which is not such a problem in terms of competitiveness for burrowers like these as it would have been their surface-living relatives; indeed, the [Eutherian] "˜true' Moles have reverted to a similar posture anyway...) The backbone features extra points of contact between some of the vertebrae, similar to the "˜xenarthrous' process that occurs in certain taxa of Eutherian mammals, which makes it stronger and relatively inflexible as a useful adaptation for digging.
Epipubic bones are present.
The males of most species possess tarsal spurs on the hind-legs, with horny sheaths, and can deliver venom (from glands in the lower thighs, behind the knees) through these both in fights with other males over mating rights and in attempts to discourage predators... or zoologists. (This is another trait shared with the Monotremata.)
Senses
The sense of smell is keen, and the brain's olfactory bulb is relatively large in order to process this data. The sense of sight, being of little use to subterranean animals, has become reduced in quality. The eyes are relatively small compared to those of most surface-dwelling or aquatic mammals, and may even be missing altogether in some members of certain species although only one of the extant species consists entirely of eyeless individuals: Colour vision, if present at all, is probably no better than dichromatic (as in most other mammals) rather than trichromatic (as in Humans & other Primates). The sense of hearing is also generally of less use to habitual burrowers than it is to surface-dwellers, and is also relatively weak in this group's members. The outer ears consist of simple holes, with ear-drums but without pinnae [surrounding flaps, to collect & focus sound]; and, although the middle ears are basically "modern" in structurewith the standard system of three bones to transmit vibrations inwards (but with adaptations shifting their audial ranges towards the low-frequency end of the scale),the inner ear ["˜Cochlea'] is only curved [as is also the case in the even more primitive Monotremata] rather than spiral & thus capable of greater sensitivity as in the "higher" mammals.
Reproduction & relevant anatomy
Females' entry into breeding condition seems to depend on food supply, and the length of time since their most recent litters were weaned, rather than on either the seasons or a regular cycle of some other kind. Pseudotalpids are viviparous, but do not develop chorioallantoic placentas and thus can give birth only to relatively undeveloped young [or "˜neotates'] which are basically similar to those of the Marsupials. Individuals of both sexes have a cloaca, but males do have an external penis although (as their testes remain internal) not a scrotum too. In both sexes the ventral surface ahead of the cloaca bears a "˜marsupial groove' which can be partially closed by a pair of lateral flaps: This contains the nipples (two of them, arranged basically one ahead of the other rather than side-by-side), and in males it protects the penis during burrowing. The womb is forked ["˜bicorniculate'], and thepenis has a forked ["˜bifurcated'] tip as well, which are also traits shared with the Marsupials. A pregnant female will normally develop one embryo in each side of her womb simultaneously, with a gestation period of 10 to 20 days depending on species.Neonates remain attached to their mother's teats for approximately one week after birth, but are then left behind in a hidden underground nest while she goes out foraging alone. Males play no part in raising their offspring.
Mammaliformes "“ Mammalia "“ Theriiformes "“ Holotheria "“ Trechnotheria - Symmetrodonta.
(The Monotremata[i.e. Duck-Billed Platypus & Echidna] are "˜Mammaliformes "“ Mammalia', but not "˜Theriiformes''; Both the Metatheria [which includes the Marsupialia] and the Eutheria [which includes the Placentalia, e.g. ourselves] are "˜Mammaliformes "“ Mammalia "“ Theriiformes "“ Holotheria "“ Trechnotheria "“ Cladotheria - Zatheria'.)
Extinct taxa: Spalacotheriidae, Zhangeotheriidae [both = RL-only, not known in IDU; early Cretaceous to end of Cretaceous]; Chronolestes [also RL only; Palaeocene... inclusion in this group disputed].
Extant taxa: Pseudotalpidae [IDU-only, not known from RL; a few fossils from mid-Miocene, then Pleistocene & modern].
Pseudotalpidae ("˜False Moles')
(c.f. "˜true' Moles, Golden Moles [RL Africa], & Marsupial Moles [RL Australia]).
Geographical Range
IDU "˜South Continent', in most areas where the soils are generally neither too thin nor too water-logged for burrowing.
Lifestyle
All of the extant species are burrowers, whose members spend almost all of the time underground, but depending on species they may either excavate networks of permanent tunnels at varying depths or "swim" through loose soil and sandcloseto the surface.Digging is carried out primarily using the shovel-like forepaws, although the hind-limbs are often also employed for moving loose material aside. Unlike the "˜true' Moles, however, they do not include any semi-aquatic species. Adults of both sexes are solitary, except for the brief periods when females are in breeding condition. The species that create permanent burrows are territorial in nature, but the "˜sand-swimmers' are apparently nomadic and non-territorial instead.
Most species' members feed mainly on earthworms, beetle larvae, and other subterranean invertebrates, but "” especially in the larger species "” they may also take some small vertebrates [most often lizards] as well if &when the opportunity occurs. Some species actually burrow deliberately into the nests of social insects rather than expend the energy that would be needed to seek out enough of those small food-items individually. Prey is always seized using the mouth, rather than with the paws, although the forepaws are used sometimes to push targets into suitable positions for ingestion. There have been confirmed cases of cannibalism in the wild, in at least two species, but this seems to occur only when other food is extremely scarce and [data anecdotal, unconfirmed] only on a same-sex basis.
Skeletal Anatomy
The jaw/skull connection is fully "˜mammalian' in form, with two of the bones on each side that are part of this in other vertebrates moved upwards into the middle ear.
Dental formula = I3 C1 P4 M4.
Their molars are triconodont & symmetrodont but not tribosphenid, without a well-developed talonid, and are acutely triangulated in cross-section.
The postcranial skeletonis also basically modern, although with [short] lumbar ribs still included, but features a "˜primitive' hip-joint that leaves them with a "˜semi-sprawling' posture (which is not such a problem in terms of competitiveness for burrowers like these as it would have been their surface-living relatives; indeed, the [Eutherian] "˜true' Moles have reverted to a similar posture anyway...) The backbone features extra points of contact between some of the vertebrae, similar to the "˜xenarthrous' process that occurs in certain taxa of Eutherian mammals, which makes it stronger and relatively inflexible as a useful adaptation for digging.
Epipubic bones are present.
The males of most species possess tarsal spurs on the hind-legs, with horny sheaths, and can deliver venom (from glands in the lower thighs, behind the knees) through these both in fights with other males over mating rights and in attempts to discourage predators... or zoologists. (This is another trait shared with the Monotremata.)
Senses
The sense of smell is keen, and the brain's olfactory bulb is relatively large in order to process this data. The sense of sight, being of little use to subterranean animals, has become reduced in quality. The eyes are relatively small compared to those of most surface-dwelling or aquatic mammals, and may even be missing altogether in some members of certain species although only one of the extant species consists entirely of eyeless individuals: Colour vision, if present at all, is probably no better than dichromatic (as in most other mammals) rather than trichromatic (as in Humans & other Primates). The sense of hearing is also generally of less use to habitual burrowers than it is to surface-dwellers, and is also relatively weak in this group's members. The outer ears consist of simple holes, with ear-drums but without pinnae [surrounding flaps, to collect & focus sound]; and, although the middle ears are basically "modern" in structurewith the standard system of three bones to transmit vibrations inwards (but with adaptations shifting their audial ranges towards the low-frequency end of the scale),the inner ear ["˜Cochlea'] is only curved [as is also the case in the even more primitive Monotremata] rather than spiral & thus capable of greater sensitivity as in the "higher" mammals.
Reproduction & relevant anatomy
Females' entry into breeding condition seems to depend on food supply, and the length of time since their most recent litters were weaned, rather than on either the seasons or a regular cycle of some other kind. Pseudotalpids are viviparous, but do not develop chorioallantoic placentas and thus can give birth only to relatively undeveloped young [or "˜neotates'] which are basically similar to those of the Marsupials. Individuals of both sexes have a cloaca, but males do have an external penis although (as their testes remain internal) not a scrotum too. In both sexes the ventral surface ahead of the cloaca bears a "˜marsupial groove' which can be partially closed by a pair of lateral flaps: This contains the nipples (two of them, arranged basically one ahead of the other rather than side-by-side), and in males it protects the penis during burrowing. The womb is forked ["˜bicorniculate'], and thepenis has a forked ["˜bifurcated'] tip as well, which are also traits shared with the Marsupials. A pregnant female will normally develop one embryo in each side of her womb simultaneously, with a gestation period of 10 to 20 days depending on species.Neonates remain attached to their mother's teats for approximately one week after birth, but are then left behind in a hidden underground nest while she goes out foraging alone. Males play no part in raising their offspring.