| Hulitherium | |
|---|---|
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| Side (a) and underside (b) views of theHulitherium skull | |
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| Hulitherium restoration | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Infraclass: | Marsupialia |
| Order: | Diprotodontia |
| Family: | †Diprotodontidae |
| Subfamily: | †Zygomaturinae |
| Genus: | †Hulitherium Flannery & Plane, 1986 |
| Species: | †H. tomasetti |
| Binomial name | |
| †Hulitherium tomasetti Flannery & Plane, 1986 | |
Hulitherium tomasetti (meaning "Huli beast", after theHuli people)[1] is an extinctzygomaturinemarsupial that lived inNew Guinea during thePleistocene. The species name honours Berard Tomasetti, a Catholic priest in Papua New Guinea, who brought thefossils to the attention of experts.[1][2]
While excavating a bank to widen the Pureni Mission airstrip inWabag, New Guinea, to comply with new regulations, theHuli workers unearthed fossils in 1967. They reportedly were frightened by their discovery as bones in their culture are associated withthe ancestors, so the material was somewhat damaged by their inquisitive prodding until they were brought to the attention of Father Bernard Tomasetti, who recognized the significance. Geologists Paul Williams and Michael Plane subsequently headed field expeditions in the area beginning in 1969 in search of more remains.[2]
Among the material was the partial skeleton of adiprotodontid, catalogue number CPC 25718, comprising: a well-preservedskull, several detachedteeth, a fragment of themandible, somecervical vertebrae (neck vertebrae), an almost completehumerus (in the forelimb), and some fragments from afemur andtibia (the hindlimb). In 1986, mammalogistTim Flannery and Planedescribed it asHulitherium tomasetti, thegeneric name honouring the indigenous Huli people for discovering the creature, andspecific name Father Tomasetti who ensured it was brought to scientific eyes.[2]
A log discovered in the samebed as the holotype wascarbon dated to roughly 38,600 ± 2,500 years ago. The Pureni site is a 2,000 m (6,600 ft) marinelimestone sequence stretching from theLate Oligocene to thePliocene, until it was filled in bylava about 850,000 years ago byMount Iumu during theMiddle Pleistocene. Infrequent volcanism in the area continued fromMount Rentoul,Mount Sisa, andDoma Peaks. The most recent deposits dating to theHolocene consist ofpeat,clay, andash.[2]
In either half of the upper jaw,Hulitherium has threeincisors (I1–3), nocanines, onepremolar (P3), and fivemolars (M1–5). As for the lower jaw, it is only known that it has a premolar (P3) and five molars (M1–5) on either side. The first incisor was the largest, and the second the smallest.Hulitherium has an unusuallyhigh-arched palate (the roof of the mouth).[2] The snout is quite narrow and has an almost-oval-shaped cross-section. Thefrontal bone (forehead) juts up suddenly from the snout, and there is a depression on its midline. Theeye sockets are placed fairly low on the skull, about 3 cm (1.2 in) above the P3 socket. There is a weaksagittal crest running along the midline of the braincase. Thepterygoid bones (behind the mouth) were probably enlarged.[2]
Theatlas (the firstcervical vertebra, in the neck) is somewhat more reinforced than might be expected for its skull size, though theoccipital condyles (which jut out from the skull to connect to the atlas) are unusually short relative to other marsupials. Another cervical vertebral centrum was preserved, measuring only 16 mm (0.63 in), which may indicateHulitherium had a short neck.[2]
The only elements of the forelimb known are a single righthumerus (missing some of the middle portion) and a poorly preserved distalradial fragment (towards the wrist joint). The proximal humerus (towards the shoulder joint) as 180° of articulating surface (the part of the bone forming the shoulder joint) in the anteroposterior (front-to-back) direction, indicating considerable mobility especially in that direction. Its middle portion is remarkably narrow, only 32 mm (1.3 in) at its smallest laterally and 23 mm (0.91 in) at its smallest anteroposteriorly. The two condyles of the humerus at the elbow joint also have 180° of articular surfacing, much like inkangaroos rather than other diprotodontids.[2]
The elements of the hindlimb known are a single leftfemur (missing some of the middle portion), a gracile righttibia (missing the distal portion towards the ankle joint), and what is probably afibular fragment. Unusually for diprotodontids, thefemoral neck is greatly reduced, so that thefemoral head lies directly on top of thefemoral shaft and sticks out of the femur quite pronouncedly, which may have enhanced the mobility of the hip.[2]
Hulitherium lived inmontanerain forests and was proposed in its initial description to have fed onbamboo, as a kind-ofmarsupial analogue of thegiant panda. It was one of New Guinea's largestmammals, standing at 1 m (3 ft) tall, close to 2 m (6 ft) long, and with an estimated weight of 75–200 kilograms (165–441 lb). Flannery and Plane (1986) suggested that because little had changed since the Late Pleistocene,humans may have been the major factor that led to its extinction.[1][3][4] The head of the femur lies directly above the shaft, which along with the morphology of the humerus-ulnar joint, suggests thatHulitherium reared up on its hind legs to feed.Dental microwear results support thatHulitherium was a browser that fed on soft plant material, rather than on fibrous bamboo.[5]
Murray (1992) concluded thatHulitherium is most closely related to the New GuineanMaokopia, and that these two together are most closely related toKolopsis rotundus also from New Guinea. Black and Mackness (1999) suggested that theHulitherium clade is more closely related to the clade comprisingZygomaturus plus another undescribed genus fromAustralia, than it is toKolopsis.[1]
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