BMR Record 1972/31

c.4

COMMONWEALTH OF AUSTRALIA

DEPARTMENT OF NATIONAL DEVELOPMENT

BUREAU OF MINERAL RESOURCES. GEOLOGY AND GEOPHYSICS

Record 1972/31

MESOZOIC PLANT FOSSILS FROM NEAR CROYDON, QUEENSLAND

by

Mary E. White

The information contained in this report has been obtained by the Department of National Development as part of the policy of the Commonwealth Government to assist in the exploration and development of mineral resources. It may not be published in any form or used in a company prospectus or statement iithout the permission in writing of the Director, Bureau of Mineral Resources, Geology & Geophysics.

I I I II

I I I I I I I I I I I I I I I I

Record 1972/31

MESOZOIC PLANT FOSSILS FROM NEAR CROYDON, QUEENSLAND

by

Mary E. White

I I I I I I I I I I I I I I I I I I I I

SUMMARY

An association of seven plant species from locality CRaO! in the Croydon 1 :250 000 Sheet area, Queensland, indicates a Jurassic or possibly Lower Cretaceous age for the Yappar Member of the Gilbert River Formation in that area.

I I I I I I I I I I I I I I I I I I I I

INT RODUCTION

Specimens collected at locality CH801 in the Croydon district contain a great deal of plant material. Preservation is good. Quantities of conifer foliage are present in the form of detacheci leaflets and fragments as weli as small twigs and branchlets with attached foliage. There are several fine examples of Bennetitalean fronds of three types as well as fragments of delicate fern. Portions of lamina of a larger Dil?terydinous fern also occur and there are two leaves of Sagenopteris.

Descriptions of the plants identified and details of occurrence of the species elsewhere in Australia follow.

Locality

The plant fossils were collected at Pt CR801, 19 km ENE of Croydon, 8 km due north of the Croydon-Georgetown Road, west of the Carron River (Croydon Re 9, photo run 2/112; grid reference (yards) 563718).

The specimens are from a boulder of siltstone from a thin, discontinuous bed in a coarse to medium-grained sandstone sequence preserved in a m·9sa. There are no other big mesas nearby to the north; several to the southwest were not sampled. Because plant fossils are present the siltstone is regarded as part of the Yappar Member of the Gilbert River Formation.

Museum specimen numbers F 23310 - F23316 - illustrated specimens F 23317 bulk of collection.

List of Plants Identified

1. Mataia podocarpoides Townrow.

2. Otozamites feistmanteli Zigno.

3. Pachypteris crassa (Halle) Townrow.

4. Pterophyllum nathorsti (Seward).

5. Hausmannia wilkinsi Walkom.

6. Sagenopteris rhoifolia Pres!.

7. ptilophyllum pecten (Phillips) Morris.

I I I I I I I I I I I I I I I I I I I I

-2-

Description of Species Identified

10 Mataia podocarpoides Townrow.

This is a Podocarpaceous conifer. It is similar in general appearance to Elatocladus planus, which was a poorly defined species in whtch milch vegetative conifer material was included. Townrow's revision of Australian conifers (1967) has resulted in elucidation of some problems of classification.

Conifer foliage of this type was described as Elatocladus conferta by A:ber, and as Palissya australis by M 'Coy, among other designations.

The leaves are bifacial, small, 1.5 cm or less, borne spirally but twisted more or less distinctly into two rows. The leaves are more or less strongly concave with projecting midribs on the lower surface. They are contracted at the base but not distinctly petiolate, the leaf widening gradually then contracting to an often acute apex. Leaf margins are not visibly thickened and the leaf substance appears to have been thin and fragile.

The species has a Triassic and Jurassic distribution.

Figure 1 of specimen F 23310 shows a number of twigs and detached leaflets of the species. Some of the other figures show further examples.

2. Otozamites feistmanteli Zigno.

The fronds of this species are typically long and slender. Pinnae are alternately arranged, slightly overlapping and not markedly auriculate but attached to the top of the rachis and obscuring it from above. Margins of pinnae are subparallel, apices truncate, rounded, and venation is fine, divergent at the base and dichotomous.

Otozamites feistmanteli occurs in the Walloon Series in Queensland. Woods (1966) states that the species is Jurassic only. It was collected from the Marburg Sandstone (Jurassic, Record 1969/57) and from the Doncaster Member (L. Cret.) in the Surat Basin in 1966 (Record 1967/78). It is distinct from species of Otozamites recorded in the Lower Cretaceous flora of the Northern Territory described in detail from the 1960 collection (Record 1961/146).

The range of Otozamites feistmanteli must be stated as Jurassic and Lower Cretaceous.

I I I I I I I I I I I I I I I I I I I I

-3-

Otozamites feistmanteli is illustrated in Figures 1 and 2. Figure 1 of specim?n F23310 shows parts of two fronds, one a basal portion with rounded pinnules similar in appearance to O. bechei, and the other a median portion of frond with elongated pinnuies. In Figure 2 of specimen F23311 a large frond is illustrated.

3. Pachypteris crassa (Halle) Townrow. (Townrow, 1965)

Figure 3 of part of specimen F23311 shows a small portion of . delicate frond, magnified x 2. The organization of the frond shows affinity with Dicroidium. The pinnules are decurrent, and the main rachis has a thin, decurrent lamina as well. Venation of each pinnule is odontopteroid. This frond is referable to Pachypteris crassa (Halle) Townrow, which is a Rhaetic - Jurassic species.

In Figure 4 of a frond on specimen F23312 is another small frond referable to the species. In Figure 5 is a very small, delicate pinna (Specimen F23313, ringed).

There is no record of the species in Lower Cretaceous horizons.

4. Pterophyllum nathorsti (Seward).

Figure 5 showing half of the top side of specimen F23313, contains part of a frond with elongated, parallel-sided pinnules with fine, parallel venation. The pinnules do not overlap, are not auriculate at the base, and are attached to the upper part of the rachis. This specimen is referable to Pterophyllum nathorsti, a pterophyllum with delicate fronds which occurs in the Jurassic of Europe, in the Walloon Series in Queensland, and in the Moolayember Formation in the 1963 and 1965 collections. (Records 1964/37 and 1966/111).

5. Hausmannia wilkinsi Walkom.

In Figure 6, of part of specimen F23313, is part of a large leaf of Hausmannia wilkinsi. A further portion of lamina is illustrated in Figure 7 (part of specimen F23314).

Hausmannia wilkinsi was described by Walkom from Plutoville, Cape York Peninsula, from Lower Cretaceous strata (Walkom, 1928). It was collected in the Surat Basin in 1966 from the Nullawurt Sandstone Member (Record 1967/78).

Dipteridinous ferns occur in Jurassic and Lower Cretaceous strata.

I I I I I I I I I I I I I I I I I I I I

-4-

6. Sagenopteris rhoifolia Presl.

Two leaves in the collection are referred to this species. One, illustrated in Figure 8, is incomplete, but the meshing of the secondary venation can be seen. The other, illustrated in Figure 9, is almost complete. Once again the venation is clear. The secondary veins ariSe at an acute angle and sweep upwards before arching to the margin. Meshing of the secondary veins is diagnostic of the genus.

The range of Sagenopteris rhoifolia is Triassic to Lower Cretaceous.

7. Ptilophyllum pecten (Phillips) Morris.

Figure 10 of specimen F23316 illustrates a frond of the species. The frond is typically narrow and elongated with pinnae closely set, alternately ar~anged, attached obliquely to the upper surface of the rachis. Fronds of this type have a Jurassic and Lower Cretaceous distribution and are very common in Australia.

CONCLUSION

The weight of plant evidence suggests a Jurassic age for the fossil horizon. However, a Lower Cretaceous age is not precluded.

REFERENCES

TOWNROW, J.A., 1965 - A new member of the Corystospermaceae Thomas. Ann. Bot., N.S., 115, 29, 495-510.

TONNROW, J.A., 1967 - On Rissika, and Mataia, Podocarpaceous conifers from the Lower Mesozoic of Southern lands. Pap. Proc. Roy. Soc. Tas., 101, 103-36.

WALKOM, A.B., 1928 - Fossil plants from Plutoville, Cape York Peninsula. Proc. Linn. Soc. N.S.W., 53(2), 148.

WOODS, J.T., HILL, D., and PLAYFORD, G., 1966 - Jurassic Fossils of Queensland. Qld Palaeontogr. Soc. Brisbane.

I I I I I I I I I I I I I I I I I I I I

-5-

WHITE, Mary E., - Bureau of Mineral Resources Records:

1961/146 - Mesozoic plant fossils from the Northern Territory. 1964/37 .; 1963 collections of plant fossils from Taroom, Qld. 1966/111 - Report on 1965 plant fossil collections. 1967/78 - Plant fossils from the Surat Basin etc. 1969/57 - 1968 collections from the Surat and Clarence-Moreton

Basins.

I I I I I I I I· I I I I I I I I I I I I

LEGENDS TO PLATES 1 and 2

PLATE 1

.Figure 1. (a) Otozamites feistmanteli. Sample F23310 (1.0 x) (b) Mataia podocarpoides. Sample F23310 (1.0 x)

Figure 2. Otozamites feistmanteli. Sample F23311 (1.1 x)

Figure 3~ · Pachypteris crassa. Sample F23311 (3.0 x)

Figure 4. Pachypteris crassa. Sample ,F23312 (4.0 x)

Figure 5. (a) Pterophyllum nathorsti. Sample F23313 (1.9 x) . (b) . Pachypteris crassa. Sample F23313 (1.0 x)

PLATE 2

Figure 6. Hausmannia wilkinsi. Sample F23313 (1. 7 x)

Figure 7. Hausmannia wilkinsi. Sample F23314 (3.5 x)

Figure 8. Sagenopteris rhoifolia. Sample F23314 (2.0 x)

Figure 9. Sagenopteris rhoifolia. Sample F23315 (2.5 x)

Figure 10. Ptilophyllum pecten. Sample F23316 (2.3 x)

Fig. I Mataia podocarpoids (0)

Otozamites fei stmantel i (b)

Fig. 3 Pachypteris crasso

. . .

Fig. 5A Pterophyllum 'nathor sti

PLATE 1

Fig. 2 Otozomites fe istmonte li

F ig. 4 Pachypteris crasso

Fig. 58 Pachypteris crassa

PLATE 2

Fig 6 Hausmannia wilkins:

Fig. 7 Hausmannia wilkins

Fig.8 Sagenopteris rhoifolia

Fig.9 Sagenopteris rhoifol ia

Fig. 10 Ptilophyllum pecten

To Accompany Record /972/3/