Restoration of an extinct elephantine marsupial (Diprotodon australis) / by Professor Owen.

  • Owen, Richard, Sir, 1804-1892.
Date:
1870
Catalogue details

Licence: Public Domain Mark

Credit: Restoration of an extinct elephantine marsupial (Diprotodon australis) / by Professor Owen. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    surfaces of which present the deep and wide longitudinal groove, as in the Tapir, Dino- there, and Kangaroo, are connected together at their base by a ridge coated thickly with cement, and extending longitudinally between the beginnings of the opposite grooves in Diprotodon. The third molar in the young specimen (Plate XLI. figs. 1 & 2, w 1) has both lobes par- tially abraded; the fore-and-aft extent of the tooth is 1 inch 10 lines, the basal breadth of both lobes is the same, viz. 1 inch 1^ line. The reticulo-punctate or “worm-eaten” character is strongly marked on the enamel of the fore part of the front lobe; this is slightly concave transversely at its upper part, the outer and inner borders inclining forward to receive the upward continuations from those ends of the anterior transverse ridge (f). The middle of the hind surface of the front lobe (Plate XL. fig. 7, a) is pro- minent, making the masticatory surface widest at that part. The prominence (b) from the opposite surface of the hind lobe looks more like an infolding of the outer border of that lobe, a character exaggerated in most Kangaroos; the inner border of the hind lobe is slightly produced backward as well as forward. The hind surface of the hind lobe does not show the mid prominence. The hind transverse basal ridge (g) is highest and thickest at its middle; the ends of this ridge are less distinctly continued upon the corresponding borders of the hind lobe than in m 2. The slight backward curve of the lobes appears in the profile view of m 1, fig. 5. In the older jaw the lobes of m 1 (Plate XL. fig. 9) are worn down nearly to their bases. The front transverse ridge rises a little above the hind one of the antecedent tooth; about 5 lines extent of the fore part of the front lobe rises above the ridge. The anterior enamel-line of the worn surface is nearly straight, the posterior one forms a low angle answering to the prominence of that surface of the lobe. The valley between the two lobes is most shallow and narrow at its middle. The abraded surface of the hind lobe is transversely elliptical, 1 inch 4^ lines in transverse dia- meter, and 8 lines in the opposite diameter; its hind border is worn down within 3 lines of the posterior basal ridge (^), which abuts against the next tooth above its anterior ridge. The fourth molar (m 2) in the younger specimen (Plate XL. figs. 9 & 10) has a line of dentine exposed on the summit of the front lobe (a), but the enamel is not worn off that of the hind lobe (5). The transverse concavity of the fore part of the front lobe is well marked at the present early stage of attrition: the convexity of the back part increases towards the base of the mid prominence. The ends of the front basal ridge [f) rise a little way upon the outer and inner borders of the front lobe. The transverse concavity of the fore part of the hind lobe is narrowed, as it descends, by the reciprocal and pro- gressive inbending of the outer and inner borders of the lobe upon the front surface, as this approaches the base of the lobe. The height of the hind lobe from the middle of the valley is 1 inch 3 lines; the antero-posterior extent of the middle of the base of the lobe is 10 lines. The posterior basal ridge {g) resembles that of ml, bearing the same proportion to the front ridge.
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