Thursday, January 29, 2015

Long-nosed Peccary (Mylohyus nasutus)

The Long-nosed Peccary (Mylohyus nasutus) was a large North American peccary that lived from the late Pliocene to the early Holocene. Among other peccaries it is most notable for its relatively large size, long legs, and elongated snout for which it is named.
Mounted skeleton of the Long-nosed Peccary at the Texas Memorial Museum
in Austin, Texas. Wiki
Etymology
The genus name Mylohyus comes from the Greek words mylo, “molar”, and hys, a female pig or sow. This name is in reference to the animal’s bunodont* cheek teeth. Nasutus is a Latin word that literally means large- or long-nosed, hence the common name for this species being the “Long-nosed Peccary”.Traditionally, other names have been attributed to other Pleistocene-age Mylohyus specimens (M. fossilis, M. browni, M. pennsylvanicus, M. lenis, M. gidleyi, and M. exortivus) based on minor variations in their teeth and skulls. Such differences are, however, more likely to be the result of sexual, individual, geographic, or temporal variation within a single species and it is now widely accepted that just one Mylohyus species was present in North America during the Pleistocene. 

Habitat & Distribution
Long-nosed Peccaries lived throughout the North American continent from the east coast to the west coast and from Canada to Central America. This species seems to have preferred to live in the well-watered woodland and forest habitats within its range. Fossils of these peccaries are typically found in association with those of other forest-dwelling animals such as tapirs (Tapirus), beavers (Castor), flying squirrels (Glaucomys), jumping mice (Zapus), and mastodons (Mammut). Unlike the contemporary Flat-headed Peccary (Platygonus compressus), Long-nosed Peccaries are rarely found in cave deposits suggesting that caves were less frequently utilized if at all.
Physical Attributes
The elongate skull of the Long-nosed Peccary comprises over a third of its total body length. Its snout, for which it derives its common name, is lengthened by long diastema* between the canines and the anterior premolars. Compared to the contemporary Flat-headed Peccary (Platygonus compressus), the Long-nosed Peccary was overall much larger in size, had longer and more slender limbs, a larger head, and a shorter tail. It retained four digits on the forefeet and three on the hindfeet. To support its large head, Long-nosed peccary had forelimbs that were slightly longer than the hindlimbs and high thoracic spines, placing its center of gravity over its shoulders. Its auditory bullae* were significantly larger than those of other peccaries, possibly indicating a superior sense of hearing.

Long-nosed Peccaries had a dental formula of 2/2, 1/1, 3/3, 3/3. The incisors are highly reduced, forming little more than rudimentary pegs. The canines are relatively small both proportionally and absolutely to those of extant peccaries and to the Flat-headed Peccary. The bunodont cheek teeth are adapted for crushing. All of the premolars are molariform and the molars themselves are quite robust and possess additional cusps, particularly the third molars.
Ecology & Behavior
Although they shared very much the same distribution, Long-nosed Peccaries are much less common in the fossil record than the Flat-headed Peccary, suggesting that the former lived in smaller social groups perhaps numbering 2 to 10 individuals. Long-nosed Peccaries also do not appear to have utilized caves as frequently as its distant cousin. Like extant peccaries they were likely diurnal and monogamous. Family groups would have would have moved around their territories in regular daily, seasonal, and annual patterns. The herd territory and individual members would be marked frequently by a scent gland on the rump. Females would have given birth to 1 to 4 precocial young which were capable of eating solid food within their first month of life.

Long-nosed Peccaries seem best adapted to browsing on the leaves, flowers, fruits, and twigs of overhanging shrubs and trees. Equipped with a flexible neck, elongated skull, and long forelimbs, it was able to access food higher off the ground than other peccaries. The cheek teeth were well equipped to handle woody plants. As with modern peccaries, the Jaguar (Panthera onca) would have been a major predator of the Long-nosed Peccary with attacks from Cougars (Puma concolor) being mostly limited to the young. There is also evidence that wolves would occasionally kill or simply scavenge from the carcasses of these peccaries as well.

Glossary*
Auditory bullae: the hollow, bony structure at the base of the skull which encloses the middle and inner ear.
Bunodont: referring to cheek teeth with rounded, bumpy cusps.
Diastema: a gap between the teeth.

References & Further Reading
Nye, April Season, "Pleistocene peccaries from Guy Wilson Cave, Sullivan County, Tennessee." (2007). Electronic Theses and Dissertations. Paper 2115. <Full text>

Lange, Ian M. "Ice Age Mammals of North America: A Guide to the Big, the Hairy, and the Bizzare". Missoula, Montana: Mountain Press Publishing Company, 2004. 161 <Book>

Westgate JW & Messick K (1985). “The Pleistocene peccary Mylohyus fossilis from Plummer Cave, Douglas County, Missouri”. Transactions of the Missouri Academy of Science 19: 99-108 <Full Article>


Lundelius EL (1960). “Mylohyus nasutus: Long-nosed Peccary of the Texas Pleistocene”. Bulletin of the Texas Memorial Museum 1 <Book>

Sunday, January 25, 2015

Peccaries: The False Pigs

The family Tayassuidae was coined by American zoologist Theodore Sherman Palmer in 1897. The name peccary is believed to be derived from a Tupi (native Brazilian) word meaning "many paths through the woods", a reference to the forest-dwelling nature of some of these animals. The four species of peccary alive today can be found in a variety of habitats including arid deserts, dense forests, and open scrublands.

Peccaries are superficially pig-like in appearance and are sometimes erroneously referred to as wild pigs or New World pigs. Both pigs (Suidae) and peccaries (Tayassuidae) possess relatively large heads with a cartilaginous disc at the tip of the snout covered in tough, leathery skin. However, this is where the similarities end. Listed below are the many important physical and behavioral differences between the two families.

Wild Boar, Sus scrofa (left) and Chacoan Peccary, Catagonus wagneri (right).

Distribution
Although fossil records show that peccaries were once present throughout North America, Eurasia, and Africa, the family has been confined to the New World since Pliocene times.

Pigs are native to Eurasia and Africa, but there is currently no evidence of them ever entering the New World until European settlers introduced them there in historic times.

Teeth
Peccaries have elongated canines that are oriented vertically and are hidden behind the lips when the jaws are closed. These teeth are ever-growing and self-sharpening, continually sliding against each other and maintaining honed tips. The dental formula for peccaries is consistent across all species; I 2/3, C 1/1, P 3/3, M 3/3 x 2 = 38 teeth.

In pigs, the canines protrude laterally and curve upward so that their tips are visible outside the mouth when closed. Because they are not contained behind closed lips, the tusks of many pig species are able to grow to quite impressive lengths and shapes. The pig dental formula is more variable among the different species; I 1-3/3, C 1/1, P 2-4/2-4, M 3/3 x 2 = 34-44 teeth.

Side-by-side comparison of the skulls of the pig (Sus scrofa) and the peccary
(Pecari tajacu). Note the sideways-pointing tusks of the pig and the more
vertically-oriented canines of the peccary.

Anatomy & Body Proportions
Peccaries have a full coat of short, bristly hairs with an erectile mane running from the back of the head to the rump. They have compact bodies with longer, more slender limb proportions adapted for swift and sustained running. All peccaries possess four toes on their front feet, although the lateral toes are highly reduced and rarely contact the ground. The rear feet may have three (as in Tayassu and Pecari) or just two (as in Catagonus) toes. The tail is vestigial* in living peccaries, barely visible within the fur of the animal and composed of 6 to 9 small caudal vertebrae. The stomach is complex and two-chambered.

Pigs have a much sparser hair covering, and those species living in the tropics may be completely bare-skinned. They are generally longer-bodied with shorter legs whose distal* elements never fuse. Although capable of considerable bursts of speed, these can only be maintained for short bursts. All species possess four functional toes on each foot. Pig tails are much longer, composed of 20+ vertebrae and are involved in non-vocal communication. They have simple stomachs.

Social Behavior
Modern peccaries are highly social and live in mixed herds that may number from five to several hundred individuals depending on the species. A scent gland is located on the lower back just above the tail, and is used in mutual grooming and scent marking. Sexual dimorphism among peccaries is weak with males and females appearing very similar externally with almost negligible differences in body size. Males and females form monogamous* pairs. Peccaries have a distinctive threat display during which they bare their tusks and produce a clattering sound by rapidly grinding them against each other. Peccaries are said to be highly aggressive and, although they may be farmed for their skins and meat, no species has been truly domesticated.

A group of pigs, called a “sounder”, typically consists of mature females (sows) and juveniles (piglets). Males (boars) are generally more solitary although they may temporarily join maternal herds. Pigs have four scent glands, two on the rump and one behind each of the front hooves which they use to mark their territories. They are polygamous* and sexual dimorphism is much more obvious, with males growing up to twice as heavy as the females and having larger tusks. Aggression is conveyed by lowering the head and charging. One species, the Wild Boar (Sus scrofa), has been successfully domesticated resulting in a global distribution.

Distal: situated away from the center of the body or point of attachment.
Monogamous: tendency to form long-term mating pairs with a single partner at a time.
Polygamous: tendency to form short-term mating pairs with numerous partners at a time.
Vestigial: a small remnant, usually of an organ or appendage, that was more developed in an ancestor.

References & Further Reading
Macdonald, David W. The Princeton Encyclopedia of MammalsPrincetonNew JerseyPrinceton University Press, 2009 <Book>

Nye, April Season, "Pleistocene peccaries from Guy Wilson Cave, Sullivan County, Tennessee." (2007). Electronic Theses and Dissertations. Paper 2115. <Full text>

Sowls, Lyle K. Javelinas and other Peccaries: their Biology, Management, and Use. College Station, Texas: Texas A&M University Press, 1997 <Book>

Fox D, Myers P. “Tayassuidae”. Animal Diversity Web. Accessed May 12, 2012. <Web Page>

Friday, January 23, 2015

Bristol's Panda (Pristinailurus bristoli)

Bristol’s Panda (Pristinailurus bristoli) is an ancient North American relative of the living Red Panda (Ailurus fulgens) from the late Miocene. Known from nearly complete skeletons, it is the most complete fossil ailurid yet discovered.
Etymology
Its genus name Pristinailurus comes from the Latin word pristinus meaning “former” or “previous”, and Ailurus for the extant Red Panda to which this species is closely related. The species is named for Larry Bristol who discovered the holotype*. Commonly, this species is also known as “Bristol’s Appalachian Panda”. The word “panda” itself is derived from the Nepalese term nigalya poonya, which means “bamboo-eater”, a reference to the diets of the living Red Panda and the unrelated Panda Bear (Ailuropoda melanoleuca).

Habitat & Distribution
Bristol’s Panda is special because it is one of only two ailurine pandas known from North America, the other being and unnamed Parailurus species from Washington State known only from a single tooth. Although the living distribution of Bristol’s Panda was undoubtedly more expansive, its fossils are known only from the late Miocene-early Pliocene locality of Gray, Tennessee. The environment in which it lived was a forested region with a subtropical climate as evidenced by the alligator and other fossils unearthed there.
Physical Attributes
Bristol’s Panda differs from the Red Panda in a number of ways, the most obvious being its much larger size. The fossil panda would have weighed 8 to 15kg (17 to 33lbs) in life, compared to the Red Panda which averages 5kg (11lbs). The skull of Bristol’s Panda is not as domed and it lacks a sagittal crest suggesting a weaker bite. However, its rostrum was longer with larger incisors and canines. The upper carnassial is also longer and less molariform*, suggesting that it was not as dependent on plant matter as part of its diet.
Skull and head comparison of Bristol's Panda (left) and Red Panda (right)
Bristol’s Panda shares several physical characteristics with the modern Red Panda which point to climbing ability including a long tail for counterbalance, broad paws with recurved semi-retractable claws, and a nimble body with powerful muscles in the forelimbs and lower back. There are, however, some major differences between the two species. Several aspects of Bristol’s Panda’s anatomy hint at a more terrestrial existence than its living relative. Compared to the highly arboreal Red Panda, Bristol’s Panda has proportionally shorter and more robust forelimbs and significantly longer hindlimbs. This body plan is typical of carnivorans* such as civets, small cats, and certain foxes that actively hunt on the ground while retaining considerable climbing ability.
Size comparison of Bristol's Panda and the Red Panda. Note the Bristol's Panda's
larger size and proportionally shorter forelimbs, longer hindlimbs, and longer body.
We see further evidence of a terrestrial lifestyle in Bristol’s Panda can be seen in the proportions of its radial sesamoid*, a bone which is found in all ailurids and in some ursids. Also known as false “false thumb" or "pandas thumb”, this bone has become mobile and able to oppose the first digits of the forepaw creating an effective clamping action. The false thumbs are particularly well-developed in the Red Panda which frequently uses them to grip tree trunks and thin branches. The false thumbs of Bristol’s Panda are proportionally much smaller, suggesting less frequent usage and overall less time spent in the higher branches of trees.

Ecology & Behavior
The body proportions of Bristol’s Panda were those of an active and agile predator that spent most of its time on the ground but could readily ascend trees when necessary. Like many small forest-dwelling carnivorans it was probably nocturnal and solitary, perhaps sleeping in burrows during the day and emerging at night to forage. Together with the Woodland Badger (Arctomeles dimolodontus), Bristol’s Panda is the most commonly found small carnivoran found at the Gray Fossil Site. This suggests that these animals had a relatively high population density, which is typical of small mammals with versatile diets. For Bristol’s Panda, the menu would have included various small vertebrates and fruits, as well as eggs and invertebrates, all of which are typically abundant in forested habitats. With food sources available all year round, Bristol’s Panda may have required relatively small territories.

Bristol's Panda appears to exhibit marked sexual dimorphism* with adult males potentially weighing up to twice as much as the females. This size variation is much more extreme than that observed in the modern Red Panda. Among modern carnivorans, high dimorphism generally occurs for one two main reasons, both having to do with intraspecific* competition. (1) Territoriality among mature males. Among highly territorial animals, males tend to be noticeably larger and more robust because they must more actively defend a territory and its resources, including any females that may live within it. Larger body size is therefore advantageous for such male-on-male confrontations. (2) Resource partitioning among males and females. Most prominent among the more solitary species, males and females living in the same environment must share the same resources. Having strongly dimorphic sexes limits competition between the sexes in that the two morphs tend to focus on slightly different food items and in different quantities. For example, the larger male will tend to select somewhat larger prey, while the female may generally focus on smaller prey. We may therefore speculate that Bristol's Panda engaged in similar social patterns, being a relatively solitary predator and forager which would actively defend feeding territories against unrelated members of the same sex.

Glossary*
Carnivoran: any member of the mammalian order Carnivora (cats, dogs, bears, hyenas, etc)
Holotype: a single physical representation of an organism that was used to formally describe it.
Intraspecific: referring to members of the same species.
Molariform: the condition in which non-molar teeth take on the form and function of true molars.
Sexual dimorphism: differences in appearance between males and females of a given species.

References & Further Reading
Fulwood EL & Wallace SC (2015). "Evidence of unusual size dimorphism in a fossil ailurid". Paleontologia Electronica 18.3.45A <Full Article>

Wallace SC (2011). “Advanced Members of the Ailuridae (Lesser or Red Pandas – Subfamily Ailurinae)”. pp 43-59 in AR Glatston (ed), Red Panda: Biology and Conservation of the First Panda <Book>

Salesa MJ, Anton M, Morales J (2005). “Evidence of a false thumb in a fossil carnivore clarifies the evolution of pandas”. PNAS 130(2): 379-382 <Full article>

Wallace SC, Wang X (2004). “Two new carnivores from an unusual late Tertiary forest biota in eastern North America”. Nature 431: 556-559 <Full article>

Roberts MS & Gittleman JL (1984). “Ailurus fulgens”. Mammalian Species 222: 1-8 <Full article>

Thursday, January 1, 2015

Red Panda (Ailurus fulgens)

The Red Panda (Ailurus fulgens) is the sole surviving representative of a family of small to medium-sized carnivorans* known as the Ailuridae, more commonly referred to as lesser pandas.
Red Panda are highly arboreal, spending the majority of their lives in trees.
Wiki
Etymology
The scientific name for the Red Panda translates literally into "Fire Cat", referencing its reddish-colored fur which also inspires its common name. Ailurus is derived from the Greek word ailuros, meaning “cat”, and fulgens comes from the Latin word fulgeo, which can mean “firey” or “flashy”. The word "panda" is derived from a Nepalese term nigalya poonya, which means "eater of bamboo". It is also referred commonly as “Red Cat-bear” or “Lesser Panda”.

When French zoologist Frédéric Georges Cuvier described the Red Panda in 1825, he thought the animal was a type of raccoon, and so placed it in the Procyonidae. In 1843, British zoologist John Edward Gray placed this species in its own family (Ailuridae) based on differences in its physiology and behavior. It was once even considered to belong to a new and now rejected family Ailuropodidae together with the Panda Bear (Ailuropoda melanoleuca) which has since been recognized as a true member of the Ursidae. Subsequent paleontological discoveries have since confirmed the Red Panda’s place in its own distinct family. Recent DNA analysis has backed this up even further.

Habitat & Distribution
It is unclear when the genus Ailurus originated, but it may have descended from the extinct genus Parailurus in central Asia sometime during the Pliocene. Other members of Ailuridae became extinct, possibly due to the drastic changes in habitat and climate that occurred toward the end of the Pliocene and continued throughout the Pleistocene. The Red Panda has persisted because it is a specialist, adapted to the temperate high-altitude forests of the Himalayas where it feeds almost exclusively on bamboo.

Physical Attributes
The Red Panda’s coat is thick, soft, and double-layered, adapted to insulate it in the cold, mountainous environment in which it lives. Its upperparts are reddish or reddish-brown in color and it limbs and underparts are black. The tail is ringed and the face has distinctive white markings.

The Red Panda is highly arboreal and demonstrates a number of anatomical characteristics that make it highly adept at climbing trees. The tail is long and used as a counterbalancing aid. Broad paws with recurved semi-retractable claws provide a powerful grip and rough paw pads enhance traction. The body is nimble with powerful muscles in the forelimbs and lower back which they use to swiftly propel themselves up vertical surfaces. Another valuable climbing tool is the radial sesamoid bone or “false thumb”. This modified wrist bone is mobile and able to oppose the first digits of the forepaw, creating an effective pincer-action ideal for clamping on to tree trunks and thin branches. This adaptation can also be used to grip and manipulate food items.
Powerful gripping forepaws and rotating ankles enable Red
Pandas to descend trees headfirst. Wiki
Red Pandas belong to a subfamily within the Ailuridae known as the Ailurinae. Members of this group display a general trend toward hypocarnivory* which is reflected by the broadening of their carnassials* and posterior premolars with the addition of grinding cusps. These changes were particularly evident in the ancestral Parailurus and further emphasized in the modern species. As noted above, the Red Panda specializes in eating bamboo. Bamboo is an extremely tough plant with a low nutritional value, and so the Red Panda has had to undergo several cranial and dental modifications to get the most out of this poor diet. The skull has become broader and more domed compared to other ailurines with a pronounced sagittal crest. The premolars have become fully molariform* to expand the grinding surface. The carnassials have completely lost their shearing function, are much wider than they are long, and have developed multiple enlarged cusps. Endowed with an immensely powerful bite for its size and efficient grinding teeth, Red Pandas are able to consume large quantities of bamboo per day.


Ecology & Behavior
Although the Red Panda feeds almost exclusively on bamboo, it will occasionally feed on the flowers, leaves, fruits, and bark of other trees while opportunistically catching small animals as encountered. Its huge paws make it very ungainly on the ground, and so most of this species’ feeding and movement takes place in the trees and it is rather ungainly on the ground.
Upper dentition (P4, M1, & M2) of the extant Red Panda (Ailurus fulgens).
Note the extreme molarization of P4 (upper carnassial) and the additional
grinding cusps adapted to crush bamboo. 
Left photo from Animal Diversity Web. Right photo from Wiki.
Because of its dense coat, Red Pandas are very heat-sensitive and find temperatures of over 25°C (77°F) intolerable. They escape the heat by being nocturnal or crepuscular* in their general habits and spend the hotter parts of the day sleeping in the shaded canopy. Red Pandas are very fastidious, grooming themselves thoroughly and regularly. Territories are defended against members of the same sex and marked are with urine and anal gland secretions. Breeding may occur from mid-January to early-March with young being born 112 to 158 days later inside a tree hollow.
Red Pandas typically avoid the midday heat by sleeping in the high branches.
Wiki.
The Red Panda is currently threatened by habitat loss throughout its range due to timber extraction, agriculture, and development. It has also been exploited for its lustrous, double-layered pelt which evolved to keep it warm in the mountainous forests in which it lives. It is now protected in all the countries in which it resides with the exception of Myanmar. An international breeding program has also been established, and it is now bred in more than 30 zoos around the world. Ultimately, the protection of this species depends on the continued protection of its remaining habitat.

Glossary*
Carnassial: specialized shearing cheek teeth found in terrestrial mammalian predators.
Carnivoran: any member of the mammalian order Carnivora (cats, dogs, bears, hyenas, etc).
Crepuscular: active during the early morning and late afternoon.
Hypocarnivore: an animal whose diet consists of less than 30% animal matter.
Molariform: the condition in which non-molar teeth take on the form and function of true molars.

References & Further Reading
Glatston, Angela R. “Red Panda: Biology and Conservation of the First Panda”. Norwich, New York: William Andrew, 2010. ISBN 1437778135 <Book>

Salesa MJ, Anton M, Morales J (2006). “Evidence of a false thumb in a fossil carnivore clarifies the evolution of pandas”. PNAS 130(2): 379-382 <Full article>


Roberts MS & Gittleman JL (1984). “Ailurus fulgens”. Mammalian Species 222: 1-8 <Full article>