Evolution and systematics
The order Paucituberculata is represented by only a single residing household, the Caenolestidae, with simply two genera. The handful of residing species is all that is still of what seems to have been a once-abundant marsupial dynasty through the Oligocene epoch, roughly 25 million years in the past. There are seven extinct households, a few of which have been described from fossils earlier than the residing caenolestids have been found, together with the Groberiidae. Some of the earliest fossils, family members Polydolopidae, date again to the Palaeocene, greater than 60 million years in the past. The decline of the paucituberculates started within the Oligocene, and it gathered tempo within the Miocene, when the continents of North and South America have been briefly joined. There was an inflow of placental mammals from the north into what had been for a lot of hundreds of thousands of years a bastion of marsupial range. The newcomers included rodents and primates whose descendants have since thrived on the expense of many ousted marsupials. A lot of similarities with different American marsupials has led some authorities to take into account the shrew opossums to be not more than a subgroup of the order Didelphimorphia. However, molecular proof helps the classification used right here—it might be that at one time the Paucituberculata have been as various because the extant Australian order Diprotodontia. Until just lately, there have been thought to be three residing caenolestid genera. The third, Lestoros, contained the species, L. inca, and is now thought-about a part of the bigger genus, Caenolestes.
Shrew opossums are all somewhat comparable wanting. The largest specimens (often males) are not more than 10 in (25 cm) lengthy, half of which is tail, besides within the Chilean shrew opossum, whose tail is comparatively quick. The face is lengthy and tapering, with a pointed snout, lengthy whiskers, and really small eyes. The ears are fairly giant and challenge effectively past the animal’s fur. The general look is comparable to a rat or overgrown shrew.
The residing shrew opossum species all derive from western South America, from the coast to the excessive Andes.
The most well-liked behavior of most shrew opossums is densely vegetated and humid–temperate rainforest, montane woodland, or the plush excessive altitude meadows of the Andean paramo. Such habitats provide cowl and an abundance of appropriate nest websites. They additionally help a wealthy invertebrate fauna and thus current good feeding alternatives.
The shrew opossums’ small dimension and the distant nature of their habitats imply they've little contact with people; consequently, particulars of their ecology and habits usually are not well-known. They are all largely nocturnal or crepuscular, and spend the day resting in hole logs or holes across the roots of bushes. They seem to reside alone, and journey across the house vary on common runways. They usually are not territorial, and a couple of particular person use the paths. They are proficient climbers, and can scramble into the branches of shrubs, utilizing the tail as a prop and a counterbalance, however not for greedy.
Feeding and weight loss program
The weight loss program is predominantly bugs and different invertebrates comparable to earthworms, which the shrew opossums discover by rummaging within the floor litter and investigating possible nooks and crannies alongside their common runways. Like placental shrews, they hunt primarily by scent; additionally they have sharp listening to, however their eyesight is comparatively poor. Various species have additionally been reported feeding opportunistically on fruit, scavenging the flesh of lifeless animals, and killing and consuming the younger of different mammals comparable to rats present in nests. No lethargic or hibernating specimens have been recorded, however there may be good proof that shrew opossums can change into lethargic in instances of food scarcity. The Chilean shrew opossum builds up reserves of fats in its tail in late summer time, which assist it survive the chilly Andean winter.
Very little is thought about caenolestid replica, together with mating system. Normal litter sizes will be beted at from the variety of teats—4 in members of the genus, Caenolestes, 5 or seven within the Rhyncholestes species. Females do not need a pouch, so nursing younger should latch on firmly to the mom’s teat so as to survive. Once milk is flowing, the teat swells within the toddler’s mouth in order that it can not simply change into indifferent. When the younger change into too huge to be carried beneath the mom’s physique, she presumably leaves them in a nest whereas she goes out to feed, returning periodically to suckle them.
The Chilean shrew opossum ( Rhyncholestes raphanurus) is listed as Vulnerable by the IUCN. Information concerning shrew opossum inhabitants density may be very restricted, since few specimens have ever been collected and discipline sightings usually are not well-known. However, the temperate rainforest during which the Chilean shrew opossum lives is shrinking shortly, and different species in the identical habitat have undergone a major decline. Caenolestes shrew opossums are most likely safer.
Shrew Opossum Species Facts
Silky shrew opossum (Caenolestes fuliginosus)
Also referred to as Ecuador shrew opossum; French: Caenolestidé d’Ecuador; German: Ekuador-Opossumaus; Spanish: Ratón musarana de los Andes. Physically, Silky shrew opossum's head and physique 3.5–5.5 in (9–13 cm) lengthy; tail 3.5–5.5 in (9–13 cm) lengthy; fur brown, tender, and shaggy, toes bear small sharp claws. It will be discovered within the Alpine areas of northern Colombia, Ecuador, and western Venezuela. Dwelling in cool, humid thickets in alpine forests and meadows. They are nocturnal, terrestrial, fast-moving; a wonderful climber. Silky shrew opossums are principally insect larvae, can even take younger vertebrate prey and carrion. Currently, they aren't but listed by the IUCN.
Chilean shrew opossum (Rhyncholestes raphanurus)
Also referred to as in French: Caenolestidé du Chili; German: Chile-Opossumaus; Spanish: Comadrejita trompuda. Physically, Chilean shrew opossum's head and physique 4–5 in (10–13 cm) lengthy; tail 2.5–3.5 in (6–9cm); might fatten prior to onset of winter. Female has 5 or seven teats. Primarily present in South central Chile and Chiloe Island; in a temperate rainforest. They are Nocturnal, terrestrial, burrows by floor litter; might enter torpor in winter. Chilean shrew opossum consumes bugs, worms, and different invertebrates caught by rummaging in topsoil and leaf litter. Chilean shrew opossum is listed as Vulnerable by IUCN.