The taxonomic and phylogenetic status of the genus is fluid. There
seems to be some disagreement among the classifiers about the number
of species and subspecies.
The six species upon which all the authorities agree are:
Dendrolagus inustus, GRIZZLED TREE KANGAROO;
Dendrolagus lumholtzi, LUMHOLTZ'S TREE KANGAROO;
Dendrolagus bennettianus, BENNETT'S TREE KANGAROO;
Dendrolagus ursinus, BLACK TREE KANGAROO;
Dendrolagus matschiei, MATSCHIE'S TREE KANGAROO;
Dendrolagus dorianus, DORIA'S TREE KANGAROO.
More recently recognized species, not yet universally catalogued are:
Dendrolagus goodfellowi, GOODFELLOW'S TREE KANGAROO
Dendrolagus mbaiso, DINGISO TREE KANGAROO
Dendrolagus scottae, SCOTT'S TREE KANAGAROO
Dendrolagus spadix, LOWLAND TREE KANGAROO
To illustrate the situation regarding classification with one example,
Goodfellow's Tree Kangaroo is classified as a subspecies of D.
matschiei by Graves, but as a separate species by others. (Evidently,
the principal distinction is the bright yellow dorsal striping of the
back and tail.) To confuse matters even more, some experts recognize
two (or three*) subspecies of Goodfellow's, Dendrolagus goodfellowi
shawmayeri and Dendrolagus goodfellowi buergersi, but buergersi is
sometimes given as a synonym for goodfellowi. Thus, depending upon the
classification system, goodfellowi could be referred to as:
Dendrolagus matschiei goodfellowi
while buergersi could be listed either as the species name for
goodfellowi itself or as a subspecies of goodfellowi. Bear in mind
that this is the state of affairs regarding a fairly well documented
animal. Things become even less clear with the recently discovered and
There is very little information about the more recently recognized
species, due to the fact that they inhabit geographically remote and
extremely small areas of Papua New Guinea that have been inadequately
surveyed by zoologists. In some cases, the species have been known to
science for only a decade or less. In addition, the populations of
some species are so small (100) as to be threatened with extinction,
thus making observation difficult. Their rarity combined with their
remoteness produce scarce data.
Generally then, dendrolagus is classified thus:
Order DIPROTODONTIA (formerly in MARSUPIALIA)
GENUS DENDROLAGUS (from the Greek, dendro - tree,
lagus - hare)
All of the wild species are under pressure from human encroachment of
their habitats. The least numerous species is in Papua New Guinea,
where deforestation and hunting have depleted the numbers to dangerous
levels. By 1999, for instance, the range of Scott's Tree Kangaroo (D.
scottae, or Tenkile in the local language) had been confined to the
south side of Mt. Sumoro in the Torricelli Mountains of northern Papua
New Guinea, an area of about 20-30 square kilometers, and the total
number of animals was thought to be perhaps as few as 100, a reduction
of perhaps 75% since the discovery of the species in 1989. All the
species are rare, however.
* Dendrolagus goodfellowi pulcherrimus, eradicated in some areas and
MARSUPIALIA; MACROPODIDAE; DENDROLAGUS (Most conservative source.)
C o n c e r n i n g C o n s e r v a t i o n
Vol 1 Issue 2, November 1999
Halting the Decline of the Tenkile
[IUCN Red List of Threatened Species - Dendrolagus spadix]
All Tree Kangaroo species, however classified, share some descriptors
in common. All inhabit similar ecological niches, the tropical rain
forest of lowlands or mountains of less than 3500 meters altitude. All
are, as the name implies, arboreal. All are herbivores (plant eaters,
mainly leaves), although they supplement their diets with the
occasional insect, bird egg or even hatchling, have body masses in the
range of 6-14 kilograms, body lengths 55-75 centimeters and tails of
55-84 cm. Males are typically larger than females (sexual dimorphism).
All are nocturnal or crepuscular (emerging at night or in the near
darkness of dusk or dawn). Like other kangaroos, Tree Kangaroos have
longer rear legs than forelegs, although the legs of the Tree
Kangaroos are more evenly proportioned, with the forelegs longer and
the rear legs shorter than in the terrestrial kangaroos.
None of the species occupies a very diverse ecological niche, although
D. matschiei and its close relative D. goodfellowi do cover a range of
altitudes where a diversity of tree species can be found, varying with
elevation. (This is true of other species, however. D. dorianus:
600-3300 m for example.) D. dorianus has the largest geographical
distribution, extending from western to southeastern New Guinea.
Generally speaking, the Australian species are contained in very
restricted areas -- sanctuaries, parks, and other protected areas. D.
scottae on New Guinea certainly has the least dispersion of any of the
species (see above).
Typical of the New Guinea ecology is this description.
"The vegetation of this ecoregion is generally tropical montane rai
forest. Although they are subject to variable climates and topography,
montane forests are smaller-crowned and have even more canopies than
lowland hill forest. Tree densities can be high, and the shrub density
is also high. Predominant canopy trees include Nothofagus, Lauraceae,
Cunoniaceae, Elaeocarpaceae, Lithocarpus, Castanopsis, Syzygium,
Illex, and southern conifers. Nothofagus and Araucaria may grow in
pure, dense stands. The levels of Myrtaceae, Elaeocarpaceae, and
conifers increase with altitude. The conifers generally found above
2,000 m include Dacrycarpus, Podocarpus, Phyllocladus, and Papuacedrus
in the canopy and emergent layer (Paijmans 1975)."
World Wildlife Fund
Northern New Guinea montane rain forests (AA0116)
Dendrolagus matschiei and D.goodfellowi
D. matschiei is confined in nature to the tropical, riparian (river),
and montane (mountain) forests of eastern Papua New Guinea, more
particularly to the Huon Peninsula and the island of Umboi (across the
strait in New Britain). The trees in the habitats can vary from
hardwoods at the lower altitudes to conifers at the higher. There are
sizable captive populations of Matschiei, but the natural population
has declined by more than 50% in a decade and is listed as seriously
endangered by the International Union for the Conservation of Nature
and Natural Resources (IUCN).
"Goodfellow's tree kangaroos are found in Papua New Guinea. They are
located in the tropical rainforests and tropical deciduous forests of
the Foya Mountains in Northern Irian Jaya and of the Owen Stanley
Ranges. They live at heights of 2267-9550 ft (680-2865 m) above sea
level." [Goodfellow's Tree Kangaroo] This extends the range of
Goodfellow's westward on New Guinea.
Silkwood leaves are the preferred food of D. matschiei in the wild,
but they follow the pattern of other Tree Kangaroos which eat a
variety foods as available, including small animals and birds. Captive
populations are fed leaves, fruit, and vegetables, with some protein
in the form of chicks and eggs. The natural tannin source that keeps
the brilliant coloration of the pelage in the wild is substituted by
tea leaves in captivity.
The only serious threat of predation comes from human beings, who hunt
the animal for food. There is a lack of large arboreal predators on
the island of New Guinea, which allows Matschiei to live unmolested in
the canopy, where its agility is its greatest protection. The
dwindling forest from clear cutting is, therefore, the most grave
threat to the survival of the species in the wild. In captivity, the
animal is at risk from mycobacterial tuberculosis that seems to be
acquired from avian contact.
Matschiei and its related species D. goodfellowi are the smallest,
most compact, and most highly colored animals of the genus. Adult
males reach a maximum body mass of 7.5 kg, while females are slightly
smaller on average. The body length of the adult males is
approximately 78 cm maximum, while females reach a body length of
about 58 cm maximum. Both males and females have tails that exceed the
length of their bodies. Tails of the males can be as long as 84 cm,
and those of females 68 cm. The tail is used for balance, and
typically is elevated when walking, which is usually accomplished on
four legs rather than two, as with terrestrial kangaroos, although the
gait of Tree Kangaroos has a pronounced hop. The forelegs are strong
and about of equal length with the hind limbs. They have long, curved
claws on the hands and feet. "They have a diastema between their third
incisor and canine of 2.95 +- 0.8 mm. The interparietal bone is large
with an acute apex." [Dendrolagus matschiei Matschie's Tree Kangaroo,
Huon Tree Kangaroo]
Matschiei are territorial and solitary except when mating. (This is in
contrast to the females of D. dorianus, which have been observed to
form friendly, cooperative groups.) The females occupy small
territories of a few acres, while males have larger territories that
overlap those of several females, allowing for polygynous mating (more
than one mate). Males are fiercely competitive for territory and the
best food resources, and for females within their territories. There
is no defined breeding season, as the females are fertile throughout
the year (polyestrous). Sexual maturity is reached at two years, and
the average female reasonably can be expected to bear six live young
during her lifetime, which can be as long as fourteen years in
captivity. "Estrous occurs every 51-79 days. Delayed implantation does
not occur in D. matschiei (but has been recorded in other Dendrolagus
species) nor is there any embryonic diapause. Gestation lasts 39-45
days, the longest recorded gestation period for any marsupial."
[Dendrolagus matschiei Matschie's Tree Kangaroo, Huon Tree Kangaroo]
(Other sources give 32 days.) The joey (infant kangaroo) is less than
an inch at birth and minimally developed. It crawls to the pouch
unassisted and attaches itself to a teat, to which it remains attached
for up to 100 days. Development in the pouch is protracted, lasting up
to 300 days. The joey emerges at that stage, returning to the pouch
regularly to suckle for approximately 2 more months, after which it
becomes self-sustaining outside the pouch.
SOURCES FOR D. MATSCHIEI and D. GOODFELLOWI
Sources are listed in order probable authenticity of data, as
refelected by the number of reliable references cited in support.
UNIVERSITY OF MICHIGAN
Dendrolagus matschiei Matschie's Tree Kangaroo, Huon Tree Kangaroo
Dendrolagus goodfellowi Tree Kangaroo
Goodfellow's Tree Kangaroo
MATSCHIE'S TREE KANGAROO (Use with caution, as it contains some
errors. Compare to the two U Michigan sites.)
In contrast to the small New Guinea species D. matschiei, Dendrolagus
bennettianus is the largest of the Australian arboreal mammals. As
with the other species, males of the Bennett's are larger than the
females, with the males weighing between 12 and 14 kg, and the females
between 8 and 11 kg. Also as with other species, body length is
shorter than tail length in both sexes. Male Bennett's are about 75 cm
long in the body with with 84 cm tails, and females have a body length
of about 70 cm with a tail length of about 80 cm. Fur is mostly dark
brown, with lighter ventral parts (chin, throat, belly), again in
contrast with the brightly colored Matschiei.
Bennett's is found in the area of Queensland (northeastern Australia)
bounded by Daintree River, Mt. Amos and Mt. Windsor, a total of less
than 4000 sq. km. It is primarily a lowland animal (450-760 m). Like
the males of other species of the genus, Bennett's males are
territorial, defending areas of up to 25 hectares. Female territories
are smaller and several are subsumed within that of a single male.
Both males and females are typically solitary.
"Dendrolagus bennettianus exhibits mostly folivory, particularly
favoring trees such as /Ganophyllum/, /Aidia/, and /Schefflera/, the
vine /Pisonia/, and the fern /Platycerium/ (Martin and Johnson, 1995).
Fruit is also taken, when available (Martin and Johnson, 1995), both
arboreally and terrestrially (Grzimek, 1990)." [Dendrolagus
bennettianus Bennett's Tree-Kangaroo]
Bennett's, unlike Matschiei which has a fairly large captive breeding
population and the habits of which have been the subject of close
scrutiny, is a wild and elusive species, and its breeding habits are
less precisely understood. Much information, consequently, appears to
be inferential, based upon the general knowledge of the habits of
other species in the genus. As a result, Bennett's is said to be an
"opportunistic" breeder, rather than a seasonal one, based upon its
tropical habitat that is largely devoid of seasonality and the fact
that other species exhibit no seasonal estrous. The joey typically
remains in the pouch until it has reached a body mass of 5 kg at about
nine months after birth. They will remain with the mother up until
sexual maturity at two years.
Bennett's suffers from human predation, although to a lesser extent
than species in New Guinea, dwelling in controlled and protected areas
where hunting is now prohibited. However, deforestation and
fragmentation of habitat have placed the species under pressure. It
does suffer some predation from dingoes and the python, although these
seem to be relatively minor perils.
University of Michigan
Lists nine species.
"Dendrolagus bennettianus, Dendrolagus dorianus,
Dendrolagus goodfellowi, Dendrolagus inustus,
Dendrolagus lumholtzi, Dendrolagus matschiei,
Dendrolagus scottae, Dendrolagus spadix,
Les kangourous arboricoles (in French)
Lists ten species.
"Dendrolague-ours (Vogelkop Tree Kangaroo) Dendrolagus ursinus
Dendrolague de Matschie (Matschie's Tree Kangaroo) Dendrolagus
Dendrolague de Lumholtz Dendrolagus lumholtzi
Dendrolague de Benett Dendrolagus bennettianus
Dendrolague de Goodfellow (Goodfellow's Tree Kangaroo) Dendrolagus
Dendrolague grisonnant (Grizzled or dusky Tree Kangaroo) Dendrolagus
Dendrolague unicolore (Doria's Tree Kangaroo) Dendrolagus dorianus
Dendrolague de Papousie Nouvelle-Guinée (Scott's Tree-kangaroo)
(Lowland Tree-kangaroo) Dendrolagus spadix
(Dingiso Tree Kangaroo) Dendrolagus mbaiso"
MARSUPIALIA Macropodidae (DIPROTODONTIA)
"42 Not listed in Wilson and Reeder (1993), see Flannery (1995a)"
Lumholtz's Tree Kangaroo (Boongarry)
"There are ten species of tree kangaroos, 2 in Queensland and 8 in New
Guinea. Of the 8 in New Guinea, they are further divided into 17
subspecies." [Unfortunately not listed.]
Given the contradictory nature of some of the information and the
scarcity of actual field observational data, it is difficult to
compile a complete summary of the genus from the Internet.
Clarification of Answer by
25 Feb 2003 07:02 PST
Questioners are encouraged to read the cited Web resources. Brief
excerpts and summaries are given in the body of the answer, but the
Web resources contain much more than the summarized and quoted matter.
Besides the information already explicitly noted and quoted in the
answer regarding the dietary and nutritional requirements and the
browsing habits of the Tree Kangaroos, the cited Web resources
provided additional information. In particular, the following pages
were cited and contain this:
Dendrolagus matschiei Matschie's Tree Kangaroo, Huon Tree Kangaroo
"Dendrolagus matschiei are almost exclusively folivorous and prefer
mature leaves. Although D. matschiei retain the large fermentation
chamber stomachs characteristic of the macropod family, their basal
metabolic rate is only 70% that of the grass eating red kangaroo,
possibly an adaptation to a diet of leaves which tend to contain more
toxins than fruit or grasses. Tree kangaroos eat sporadically
throughout the day for an average of 15-20 minutes every four hours."
Dendrolagus goodfellowi Tree Kangaroo
"They also eat flowers and grass, which are digested in their
sacculated stomachs by fermenting bacteria."
"Territories are usually centered around large trees used to roost
diurnally. These roosts are left at night for foraging amongst
preferred feed trees, which are often found toward the edge of closed
If you require further information regarding Tree Kangaroo
TREE KANGAROO (Dendrolagus spp.) Nutrition Husbandry Manual
"GASTROINTESTINAL ANATOMY/BODY MASS
The similarities of gastrointestinal anatomy between macropod
marsupials, including tree kangaroos, and ruminant ungulates have been
previously described (Moir et al. 1955; Moir 1968). The presence of a
large, complex stomach, which, when full, can weigh up to 15 percent
of the total body weight (Bauchop 1978), as well as an esophageal
groove indicate that these animals possess anatomical adaptations that
support fermentation of fibrous plant material by symbiotic
microorganisms (Hume 1982).
Just as in ruminants, the presence of an esophageal groove probably
suggests a similar function as in ruminants where this structure
serves to shunt milk past the fermentative portions of the foregut to
the enzymatic compartments of the gastrointestinal tract (GIT) (Hume
1982). While there are some minor variations seen in the foreguts of
Dendrolagus (Beddard 1923), the general characteristics are similar to
that of other macropods. However, these differences would not affect
fermentation in the foregut of the tree kangaroo (Bauchop 1978).
The symbiotic relationship with microbial organisms in the GIT allows
the "host" animal to utilize plant polysaccharides, including
cellulose and hemicellulose, as principle sources of energy; tree
kangaroos lack the enzymes necessary to degrade these compounds. As a
result, the tree kangaroo is in effect collecting food items to "feed"
the microbial population inhabiting the gastrointestinal tract, and
obtains its nutrition from the end-products of the fermentation
process. The balance of organisms within the forestomach of a foregut
fermenter is carefully regulated through a combination of intake of
appropriate substrates, pH, and removal of end-products by absorption
or movement through the GIT.
Consumption of foods which contain significant quantities of readily
fermentable carbohydrates (e.g., starch, sugars) could lead to a rapid
rate of fermentation, excessive production of fermentation end
products (i.e., CO2, CH4), a lower than normal pH in the foregut, and
a state of disbiosis (an inappropriate balance of gut microbial
organisms). For this reason, the use of commercially available fruits
and other high sugar items, should be strictly regulated and limited.
As with ruminants, pseudoruminants or camelids, and other macropod
marsupials, tree kangaroos have been observed to regurgitate the
contents of the foregut in order to reduce the food particle size by
further mastication (Whitehead, 1986). The process is called merycism,
and is a normal behavior in many non-ruminant species (e.g., tree
kangaroos) with foregut fermentation."
Bursaries for the SECOND BIENNIAL SYMPOSIUM OF THE SYSTEMATICS
Title: HAS [MACROPODINIUM] (CILIOPHORA:LITOSTOMATEA) COEVOLVED WITH
ITS KANGAROO HOSTS?
"ABSTRACT: Members of the genus [Macropodinium] are unique
enodsymbionts inhabiting the foregut of Australian macropodid
marsupials. In our survey of macropodids for ciliated protozoa we have
found 15 putative [Macropodinium] spp. occurring in 10 host species.
Ciliates were characterised by silver impregnation and scanning
electron microscopy. Species vary in size, vestibulum orientation,
pellicular ornamentation, and dorsoventral groove depth. The species
found fall into 3 groups: the [M. moiri] group are small, oval species
with deep body grooves and anterior vestibula; the [M. yalanbense]
group are medium sized, reniform species with shallow body grooves and
anterio-ventral vestibula; and the [M.] "complex" group are large,
highly ornamented species with deep body grooves and anterio-ventral
vestibula. The species groups are associated with particular host
groups. The [M.moiri] group members are found only in the primitive
genera [Setonix, Thylogale] and [Petrogale], the [M. yalanbense] group
are found in the advanced subgenera [Macropus(Macropus)] and
[Macropus(Osphranter)] and the [M.] "complex" group ciliates found in
the wallaby genera [Wallabia] and [Macropus(Notomacropus)].
Coevolution seems to have occurred at the host genus/subgenus level
but it is as yet unknown whether it has occurred at the species
CAMERON, STEPHEN (Speaker) (1), ADLARD, ROBERT (2), AND O'DONOGHUE,
1&3 Department of Microbiology and Parasitology, The University of
Queensland, Brisbane, Australia; 2. Protozoa Section, The Queensland
Museum, Brisbane, Australia.
E-mail:- 1. s.cameron&mailbox.uq.edu.au 2. RobertAd&qm.qld.gov.au
Title: THE PHYLOGENY OF THE CILIATES (CILIOPHORA: LITOSTOMATEA)
ASSOCIATED WITH MACROPODID MARSUPIALS.
"ABSTRACT: Macropodid marsupials (kangaroos and wallabies) have
endosymbiotic ciliates inhabiting their stomachs. Our investigations
of 282 animals representing 23 host species have found over 50 ciliate
species belonging to 6 genera. It is unknown whether this ciliate
fauna had a Gondwanan origin in association with primitive marsupials
or whether some or all had an Asian origin and entered Australia in
the Miocene with rodents. Small subunit ribosomal DNA of
representative species from each Australian genus was sequenced and
their phylogenetic relationships to other ciliates inferred with
parsimony and maximum likelihood analysis. The Australian genera form
a monophyletic assemblage whose sister group is the Trichostomatina,
endosymbionts of placental herbivores. The branching pattern indicates
a deep, well supported branch (90+ bootstrap values) separating the
two groups. On this basis we have concluded that the Australian
endosymbiotic ciliate fauna is of monophyletic Gondwanan origin. The
two groups of endosymbiotic ciliates within herbivorous mammals
(placental and marsupial) share a common ancestor but extant
assemblages are the result of independent parallel radiations within
different herbivorous mammalian groups."
DIGESTION IN MAMMALS (COMPUTER SIMULATION)
Manual for a computer simulation of mammalian digestion, including
that of the Macropodids (Kangaroos).
Some skeletal information was noted. Also, the cited Web pages gave
"Macropodids have a long and narrow skull, usually a long rostrum, and
a head that seems small relative to the size of the body. The
masseteric fossa on the lower jaw is deep, and a masseteric canal is
present. The macropodid dental formula is 3/1, 1-0/0, 2/2, 4/4 = 32-34
(one species has additional, supernumerary molars). Macropodids have
enlarged first lower incisors (diprotodont). Their second and third
upper incisors lie lateral to the first (vs. behind first in other
diprotodonts). This arrangement results in a continuous cutting edge
at the front of the mouth. When the animals bite, the procumbent lower
incisors do not meet the upper teeth; rather, they press into a tough
pad on the roof of the mouth, located just posterior to the upper
incisors. This arrangement is very much like that seen in bovid and
cervid artiodactyls. The canines are absent or vestigial, and a
substantial diastema separates incisors and cheek teeth. The pattern
of tooth replacement is unusual. A young kangaroo has 2 blade-like
upper premolars, which are soon shed and replaced by a third premolar
(which is also blade-like). The molars erupt in succession, with the
first falling out and others moving forward as the animal grows. The
molars of macropodids are hypsodont, quadritubercular, and either
selenodont or lophodont or a combination of the two forms."
Again, it is useful to follow the links that are placed on pages that
have been cited in an answer.
For instance, clicking on the Mammalia link on any of the University
of Michigan Animal Diversity pages will take you to these pages:
"Marsupials differ from placentals in a number of important and
obvious ways. The palate of marsupials is usually "fenestrated," that
is, it contains large gaps or spaces in its bony surface. The angular
process of the dentary is inflected (bent) medially in almost all
marsupials. The braincase is small and narrow. It houses a relatively
small and simple brain compared to that of similar-sized placentals.
The jugal is large, extending posteriorally so that it actually
contacts and forms part of the glenoid fossa. The lacrimal canal is
slightly anterior to the orbit so that it opens on the surface of the
face rather than inside the orbital space. The bullae are sometimes
not ossified, and when they are, they are formed largely by extensions
from the alisphenoid."
"The postcranial skeletons of marsupials differ from those of
placentals (but resemble monotremes) in that modern marsupials have
epipubic bones in the body wall, projecting anteriorally from the
pelvis (epipubics are vestigial in recently extinct thylacines and
were absent in at least one extinct group)."
"They can be distinguished from other metatheres because they are both
syndactylous (digits two and three of the hind feet are fully fused
except for the claws) and diprotodont (a single pair of incisors
dominates the lower jaw, although sometimes an additional pair is
present). Most diprotodonts have three pairs of incisors in their
upper jaws, but this number is reduced to one pair in one family, the
wombats. Diprotodonts lack lower canines. Upper canines are present,
but they vary in shape from low and smooth to having many sharp,
curved ridges (selenodont or lophodont)."
A Partially labelled racoon skeleton:
Additional information can be found here:
QuickTime VR of the skull (Requires Apple QuickTime VR plug-in.)
Topography, Structure and Function of the Patella and the Patelloid in
The patella is a sesamoid bone that is found in most mammals and is
regularly located in the insertion tendon of the quadriceps femoris
muscle. Up to now, only a little has been known about the topography,
structure and function of the patella in marsupials. Therefore the
stifles of 61 marsupials of 30 different species were studied by
radiography, necropsy and light microscopy. It was found that only the
family of bandicoots (Peramelidae) possessed a typical patella. The
other species revealed a patelloid consisting of fibrocartilage. The
structure of the patelloid revealed common characteristic features in
the following families of marsupials: (1) Dasyuridae, Phalangeridae,
Pseudocheriidae, and Potoroidae; (2) Burramyidae; (3) Phascolarctidae,
Vom- batidae, and Dendrolagus; and (4) Superfamily Macropodoidea
(except Dendrolagus and Potoroidae)."
"The patelloid of type III was found in specimens belonging to the
families Phascolarctidae, Vombatidae and Dendrolagus. It was
characterized by a very high degree of differentiation in the
fibrocartilage the size of which was about two-thirds of the sectional
area of the quadriceps femoris tendon. The collagen fibres were highly
interwoven and had lost their longitudinal orientation. The cells were
mainly chondrocytes surrounded by a distinct capsule and a clear
areola. As the amount of proteoglycans was very high in the ground
substance, the collagen fibres were regularly masked (Fig. 4)."
Unfortunately, it is not possible to give a complete description of
the skeleton of Dendrolagus. That would require an entire book of
skeletal anatomy. There is not much detailed, specialized skeletal
data available on the Web.
This was touched upon tangentially when it was noted that Tree
Kangaroos are susceptible to tuberculosis by inhalation. It was
assumed that a basic understanding of Mammalian physiology underlay
In brief, Tree Kangaroos are, as the cited matter showed, of the Class
Mammalia. All mammals share certain essential characteristics, among
which is that they are air breathers, possessing lungs. The mammalian
lungs exchange gaseous oxygen from the atmosphere through the alveolar
membranes with dissolved CO2 (carbon dioxide) in the red blood cells
of the circulatory system.
For a discussion of the mammalian lung, see:
Mammalian Resp Outline
Slide Suppl: Mammalian lung
Chapter 1 Homework Model Answers
"13. Breathing in mammals is regulated by medullary groups of neurons,
known collectively as the 'respiratory center.' These neurons regulate
the frequency and depth of breathing, as well as initiate respiratory
movements in the thoracic region. In the respiratory center, two types
of neurons exist: inspiratory neurons, which initiate the breathing
movement, and expiratory neurons, which initiate exhalation. These two
groups of neurons are mutually excitator, that is activity in one set
is followed a short time after by activity in the other. In mammals,
the activitiy of the respiratory neurons is influenced most strongly
by the blood pCO2 and also by the acidity of the cerebrospinal fluid.
Because carbon dioxide reacts with plasma water to form the weak
carbonic acid, pH of both blood and cerebrospinal fluid is inversely
related to blood pCO2. In fishes, it seems to be the blood pO2 that
regulates breathing, and not pCO2. Presumably this is because the
scarce commodity in water is oxygen, and so regulation of respiration
needs to center around the maintenance of blood pO2 in a variable
oxygen environment. In air-breathing mammals, however, environmental
pO2 is constant and abundant, and it is CO2 that is hard to get rid
of. Breathing regulation is centered around the need to adjust the
blow off of CO2 to metabolic production of this gas."
"14. The mammalian lung, however, uses an elastic thoracic cage and a
diaphragm to fill the lungs by suction - that is, lung pressure during
filling of the lungs is less than the atmospheric pressure."
Dendrolagus matschiei Matschie's Tree Kangaroo, Huon Tree Kangaroo
"Routes of infection are assumed to be similar to those in humans:
inhalation of infectious aerosols or inoculation from wounds or