The Origin of the Lower Devonian Fauna of Reefton, New Zealand; with Notes on Devonian Brachiopoda.
[Read before the Canterbury Branch, May 11, 1942; received by the Editor, May 15, 1942; issued separately, September, 1942.]
In discussing this problem in 1935, the writer (Allan, 1935, pp. 34–6) explained the remarkable resemblance between the characteristic fossils of the Reefton argillites and those of the Upper Siegenian-Lower Emsian of the standard Western European development of the Rhenish facies, by advancing hypotheses which now appear to be untenable.
The main hypothesis was that units of a cosmopolitan Lower Devonian fauna isolated geographically, i.e., not connected by shore-lines, would, if subjected to, or stimulated by, a similar set of environmental controls, contain closely related characteristic fossils.
The reasons for this conclusion were (1) the apparent lack of evidence of faunas of the same facies along possible routes of migration between Europe and New Zealand; and (2) the belief that certain Lower Devonian species-groups of brachiopods, notably the gens of Spirifer hercyniae Giebel, and the Leptostrophias, were of world-wide occurrence.
In order to explain the cosmopolitan distribution of brachiopods without recourse to migration along shore-lines it was necessary to put forward the subsidiary hypothesis that these Lower Devonian forms must have possessed much greater powers of larval distribution than do Recent members of this phylum.
Recent work by Shirley (1938) and Caster (1939) suggests that the reasons which appeared to necessitate the main hypothesis are no longer valid. It must, therefore, be rejected, and with it will go the subsidiary hypothesis which was weak from birth.
Shirley (1938, pp. 491–496) has shown that the Bohemian Koneprusy facies, represented in New Zealand by the Baton River Beds, occurs at intervals between north-western France and New Zealand. He suggested that the coastlines of the period run more or less in the same general direction, and that “The general distribution … suggests the existence of a Lower Devonian ‘Tethys,’ the shores of which provided the means by which the shallow-water faunas could spread over long distances” (1938, p. 494).
He also quoted evidence to suggest that the fauna of the more littoral Rhenish facies to which the Reefton fauna belongs, had migrated along a parallel route; recording Rhenish elements from Moravia and the Altvatergebirge in south-eastern Europe; from the Altai and Koktschetau; and from Kwangsi, southern China. Shirley wrote: “The evidence which Allan needed is, therefore, to some extent, supplied by these records. Future exploration will doubltless add to them” (1938, p. 495).
The case for the Bohemian facies is much stronger than that for the Rhenish type. For the latter the picture is not entirely convincing. All the records cited by Shirley refer to areas which presumably formed parts of the northern littoral of Tethys, and the nearest is
still a very long way from New Zealand. Nevertheless, if the acceptance of the hypothesis of a Lower Devonian Tethys in explanation of the distribution of the Bohemian facies is justified on the available evidence, it must also be accepted for the Rhenish facies.
Shirley (1938, pp. 495–6) suggested tentatively that the presence of North American species in the Lower Devonian of New Zealand might be explained by migration along a circum-Pacific route such as was operative in the Triassic period. In this connection Caster's hint (1939, pp. 183–4) of a relationship between New Zealand and northern South America in the Devonian should engender caution.
There is also to be noted Du Toit's hypothesis (1937) of a southern geosyncline, the Samfrau, by which interchange between New Zealand and the “austral” Devonian area of South Africa and South America was possible. This sea-way might presumably have joined the New Zealand section of a circum-Pacific and Tethyan route. The writer, however, deliberately refrained from stressing—in fact minimised the importance of—the insignificant “austral” element in the Reefton fauna, and is of the opinion that Du Toit's hypothesis, whatever its merits on other grounds, is not strengthened by the data presented in the Reefton Bulletin.
In regard to the second reason for the writer's hypothesis of 1935, viz. that certain species-groups of brachiopods had a cosmopolitan distribution in Lower Devonian times, the work of Caster (1939) on the Colombian faunas show that it is probably erroneous.
In just those species-groups on which the writer placed most reliance Caster demonstrated a marked development of homoeomorphy. For example, the writer referred to the genus Acrospirifer certain South African-South American species which, on closer study, Caster placed in a new genus Australospirifer. In discussing Acrospirifer which occurs in the Columbian fauna he stated: “It is truly amazing … that none of the superficially similar forms hitherto described from South America and South Africa can be satisfactorily assigned to the same generic group” (1939, p. 155); and continued the “‘austral’ forms may well be assigned to distinct, albeit homeomorphic genera.” (1939, p. 156.)
The writer referred Leptostrophia concinna (Morris and Sharpe) of the “austral” Lower Devonian to the species-group of L. magnifica (Hall) and the European L. explanata (Sowerby). Caster (1939, p. 85) suggested that the “austral” species is to be grouped with Protoleptostrophia and is not closely related to L. magnifica of North America.
It is thus clear that new records of Lower Devonian faunas of both the Rhenish and the Bohemian facies, together with the demonstration of widespread homoeomorphy among Lower Devonian brachiopods leading to the recognition of generic groupings at variance with those suggested by the writer, undermine the earlier reasoning, and force the rejection of an untenable hypothesis.
In its place the writer is constrained to accept the view that the origin of the Lower Devonian fauna of the Reefton Beds is to be explained by migration along shore-lines by a route or routes still imperfectly known but of which the most probable and important was the Tethys sea-way.
Notes on Devonian Brachiopoda.
Genus Cymostrophia K. E. Caster, 1939.
Bull. Amer. Paleont., No. 83 (April 8), pp. 39–40.
Type (by original designation): Leptaena stephani Barrande, 1848.
Cymostrophia stephani (Barrande).
1938. Stropheodonta stephani (Barr.), Shirley, Quart. Journ. Geol. Soc., Lond., xciv (4), pp. 469–470, pl. XLI, figs. 11–12.
Remarks: Caster, in a brief comment on Shirley's monograph, stated: “Shirley's Stropheodonta stephani (Barrande) is indubitably closely allied to Barrande.'s species, and is therefore certainly assignable to the new genus Cymostrophia of which Barrande's species is the genotype.” (1939, p. 183.)
According to Caster, this genus, which belongs to the Douvillinoid Stropheodontids (family Stropheodontidae) is typically boreal, occurring in the Helderbergian, Oriskanian and Ulsterian series of North America, and in the Koneprusy F2 fauna of Bohemia. Caster described three new species from the Devonian of Colombia (the Floresta Fauna), but the genus is not known from the “austral” faunas of the remainder of South America or from South Africa.
C. stephani (Barrande) is one of the most abundant species of the Baton River Beds.
Genus Rhytistrophia K. E. Caster, 1939.
Bull. Amer. Paleont., No. 83 (April 8), pp. 86–7.
Type (by original designation): Stropheodonta beckii Hall.
Rhytistrophia shirleyi n.sp.
1938. Leptostrophia explanata Shirley, Quart. Journ. Geol. Soc. (Lond.), xciv (4), p. 468, pl. XLI, figs. 7–9 (not of J. de C. Sowerby, 1842).
Holotype, in the Auckland University collection, the original of Shirley's plate XLI, fig. 8, the internal cast of a ventral valve (M654).
Remarks: Caster proposed this genus for a group of corrugated Leptostrophids which occur in the North American Devonian (Helderbergian to Erian), and in the Venezuelan-Colombian Devonian areas of South America. The same author pointed out that Shirley's “Leptostrophia explanata (Sowerby) will bear comparison with Rhytistrophia caribbeana (Weisbord) from the Cachira series of Venezuela and the variety colombia [Caster] from the Colombian Floresta series.” (1939, p. 183.)
A comparison of Shirley's pl. XLI, figs. 7–9, with pl. 5, figs. 5, 6, and 13 of Caster's monograph seems to me to justify this conclusion. Leptostrophia explanata (Sowerby) belongs to a distinct generic group as Caster (1939, p. 97) has pointed out. I am unable to add to the description given by Shirley, and, until well preserved dorsal interiors are collected, Shirley's description will serve as a diagnosis of the new species.
It may be noted that Leptostrophia reeftonensis Allan which I compared with L. magnifica Hall and L. explanata (Sowerby) is in need of a new generic location (cf. Caster, 1939, pp. 85–86). This question may be left in abeyance until the publication of Caster's promised monograph on ε the crenulate-hinged Strophomenacea.
Genus Hysterolites Schlotheim, 1820.
1820. Hysterolites Schlotheim, Die Petref., pp. 247–250.
Type: H. hystericus Schlotheim, 1820.
Hysterolites cf. hystericus Schlotheim, 1820.
1935. Acrospirifer cf. hystericus (Schlotheim), Allan, N.Z. Geol. Surv. Pal. Bull., No. 14, p. 19, pl. II, figs. 4–5.
Remarks: The genus Acrospirifer Helmbrecht and Wedekind, 1923, was employed by Allan (1935, pp. 18–19) for a group of Lower Devonian species in which A. hystericus (Schlotheim), from the Lower Siegenian, was believed to be the earliest Devonian stage of an evolutionary sequence leading through primaevus (Steininger) to hercyniae (Giebel) and paradoxus (Schlotheim). Unfortunately, Allan failed to investigate the generic name Hysterolites Schlotheim, 1820, of which, according to Schuchert and Le Vene (1929, p. 69), the genolectotype is H. hystericus Schlotheim. If the generic name is to be used for the complete gens of Spirifer hercyniae Giebel (Allan, 1935, pp. 15–17), then Hysterolites Schlotheim should be substituted for Acrospirifer Helmbrecht and Wedekind.
If, on the other hand, the sequence of species which the writer, following Scupin (1900, p. 132) regarded as a single lineage is not really such, it may be possible to retain both generic terms. This, apparently, is the position adopted by Shirley (1938, pp. 480–1), who used Hysterolithes for Spirifer subspeciosus (de Verneuil) and Acrospirifer for Spirifer arduennensis (Schnur). The same usage was employed by Maillieux in 1933*1*
Genus Schizophoria W. King, 1850.
1850. Schizophoria King, Mon. Permian Foss. (Pal. Soc.), pp. 105–6.
Type (by original designation): Anomites resupinatus Martin, 1809, Petref. Derb., t. 49, figs. 13–14.
Schizophoria cf. provulvaria (Maurer, 1893).
1935. Proschizophoria cf. provulvaria (Maurer), Allan, N.Z. Geol. Surv. Pal. Bull., No. 14, pp. 11–12, pl. III, figs. 4 and 7.
Remarks: In their revision of the Orthoidea, Schuchert and Cooper (1932, p. 143) placed Maurer's species in the genus Schizophoria; so also did Shirley (1938, p. 465). Schuchert and Cooper referred Proschizophoria to the Dalmanellidae; Schizophoria to the Schizophoriidae.
There is no justification for the position adopted, by the writer.
Allan, R. S., 1935. The Fauna of the Reefton Beds (Devonian), New Zealand, N.Z. Geol. Surv. Pal. Bull., No. 14, 72 pp., 5 pls.
Caster, K. E., 1939 A Devonian Fauna for Colombia, Bull. Amer. Paleont., 24 (No. 83), 218 pp., 14 pls.
Du Toit, A. L., 1937. Our Wandering Continents. Edinburgh and London, 366 pp. (Reference to text-fig. 7 and pp. 62–3 and 65.)
Schuchert, C., and G. A. Cooper, 1932. Brachiopod Genera of the Suborders Orthoidea and Pentameroidea, Peabody Mus. N.H. Mem., 4 (1), 270 pp., 29 pls.
—– and C. M. Le Vene, 1929. Brachiopoda (Generum et Genotyporum Index et Bibliographia), Foss. Cat., I Anim., Pars 42, 140 pp.
Scupin, H., 1900. Die Spiriferen Deutschlands, Pal. Abhandl., N.F., Bd. IV, Heft 3, 140 pp., 10 pls.
Shirley, J., 1938. The Fauna of the Baton River Beds (Devonian), New Zealand, Quart. Journ. Geol. Soc. (Lond.), XCIV (4) (Dec. 30), pp. 459–506, pls. XL–XLIV.
[Footnote] * (1) Terrains, Roches et Fossiles de la Belgique, ed. 2, 1933, pp. 47 et seq.