«A C TAP A L A EON T 0 LOG I ·C A. P OL 0 N I C A No. I Vol. IV I 9 5 9 ROMAN KO ZLOWSKI &.p A L GREGUSS DISCOVERY OF ORDOVICIAN LAND PLANTS ...»
A C TAP A L A EON T 0 LOG I ·C A.. P OL 0 N I C A
Vol. IV I 9 5 9
ROMAN KO ZLOWSKI &.p A L GREGUSS
DISCOVERY OF ORDOVICIAN LAND PLANTS
(Preliminar y communication)
In O rd ovician er ra tic boulder s land pl ants rema in s were found. They
Abstract. could be considered a s more p rimitive than P silophyta les, a nd probably a s the mo st prim it ive land plants. Two new genera : Mttsciphyton gen. nov. a n d H epaticaephyton gen. no v. a re distin gu ished.
1. INTRODUCTIO N by
R O M AN KOZLOWSKI(Wars za w a, P oland) Fo r the purpose of etching from Ordovician calcareous rocks graptoli tes and other animals with. chitinous skeleton the present writer has, for many years past, used the hydrochloric and acetic acid treatment..
Recently, during this work, he has discovered plant remains of particular interest.
The rocks which have yielded these organisms are erratic boulders car r ied to Poland from Scandinavia and the Baltic region by Pleistocene g laciers. Besides pulverized or minute fragments of calcareous animal s keletons, they practically always contain numerous remains of chitinous skeletons, such as Graptolithina, Annelida (jaws) and Hydroida. Occasionally they also yield plant remains. The majority of these are referable to Phycomycetes and Algae. They occur in association wi th a ty pically marine fauna and, most likely,' we r e themselves marine organisms.
Sporadically, however, among these aquatic plants, other remains are noted of hi gher organization · and.su rely of continental origin. These specimens have attracted the writer's attention as evidence of particular interest.
During his visit, in the summer of 1958, to the Institute of Palaeontology directed by the writer, Professor P. Greguss from the Szeged University (Hungary) showed a keen interest in the mentioned material.
These peculiar plant remains were, consequently, entrusted to hi d; for in vestiga tion. The present brief report and theoretical speculations by Professor Greguss are introductory to a future more detailed description of these uncommonly interesting materials by this author.
ROMAN KOZLOWSKI & PAL GREGUSSThe plants, for which Professor Greguss has introduced the new generic name of Musciphyton gen. nov., were extracted from a boulder (No. 0.225), 1.65 kg in weight, collected near Zakroczym, in the valley of the Vistula. It is a compact pelitic limestone, lithologically similar to the lithographic limestone of the Jurassic. This rock, familiar long since to geologists who study the erratic boulders of northern Europe, is by German writers referred to as "Ostseekalk". The graptolite Orthograptus gracilis (Roemer) is its most common index fossil. Its age most probably corresponds to that of the "S aun ja" (F ja) horizon, that is to the middle part of the Estonian Upper Ordovician. The mentioned graptolite has not been found by the writer in the boulder which has yielded Musciphyton gen. nov., but the lithological features of that rock prove beyond doubt that it is a typical "Ostseekalk". Fine calcareous dust constitutes the bulk of this limestone, and small concentrations of pyrite and organic remains are dispersed in the matrix. The organic remains contain silicified shells of Brachiopoda Articulata (Orthoidea and Plectambonitidae), phosphatic shells of Brachiopoda Inarticulata (Conotreta sp.), Conodonta, pyritized spicules of sponges, chitinous remains of Annelida (Scolecodonta), Hydroida and Chitinozoa. Among.these animal remains occur fairly numerous thread-like aggregations of Phycomycetes, sometimes partly pyritized, but in most cases not displaying any fossilization.
Specimens of Musciphyton gen. nov. occur under most peculiar form.
The majority constitute associations of several stems united, mostly at their base, by a matrix of mineral detritus. Unsorted quartz grains predominate, ranging from fine powder to 360 j.L in diameter. The larger grains are usually rounded, the smaller - angular. In most cases the quartz is colourless, very rarely of milkish-pink or light mauve tint.
Grains of glauconite and rare flakes of strongly weathered biotite also· occur. The mineral detritus here is usually coated by iron oxides of an orange or red colour. The mineral associations cementing stems of Musciphyton are doubtlessly an alien element in the calcareous deposit. Most likely it is the substratum on which these land plants developed and together with which they were secondarily transported to a marine environment.
Dense associations of threads (hyphae) of Phycomycetes most likely referable to saprophytes, commonly occur on stems of Musciphyton and within the mineral detritus.
Boulder No. 0.241, one kg in weight, which has yielded plants, by Professor Greguss called Hepaticaephyton gen. nov., was also collected near Zakroczym. It is a limestone with granular texture, almost entirely made up of calcareous fragments of indeterminate Brachiopoda and tests of Echinodermata. · Juvenile gastropod shells and less frequent conodont.
DISCOVERY OF ORDOVICIAN LAND PLANTS 3denticles are encountered among these fragments. Chitinous remains are not com m on, being mainly those of Scolecodonta and Chi tin ozoa. P h ycomycetes are abundant. The age of this boulder can no t be exactly deter mi ned on t he animal remains it con tains. Scolecodonta an d Ch itino zoa are com mon forms in Middle and Upper Or dovician boulders. Closer investigation of t hese remains may in the future lead to a more exact dating of this boulder. For the present, however, it is established as Ordovician.
The specimens of Musciphyton and Hepaticaephyton are w onderfully well pr eser ved. After dissolution of the original calcite which impregnated the plant tissues, they have nearly a recent plant semblance. Their brown colouration is occasionally so faint that they are almost colo urless, in other specimens it is stronger. The majority of stems are not compressed and have pr ese r ved their original plasticity. The con tours of the large epidermal cell s coa ting t he sur face are in most cas es very distinct. After being etched the tissues of these plants, however, still remain more or less impregnated by quartz powder, pa rtly also by that of pyrite which has not dissolved by acid treatment.
Abundant Phycomycetes, accompanying these plants, are likewise excellentl y preserved. There are mainly associations of ve r y fine colourless hyphae, non-mineralized or occasionally in a varying de gree filled or incrusted by pyrite. Their original plas ticity has persisted he re too.
Numerous vesicles (sporangia) are attached to some of them. In appearance these Or dovi cian Phyco mycetes resemble Palaeomyces which occur in the Middle Devonian of Scotland in association with silicified remains of Psilophytales. These plants must have been common in Or dovician seas, as they freque ntly occur in rocks of t hat age.
Speculations on the nature of the first Cormophyta which started land vegetation, and on the period of Earth's history which witnessed the expansion of the vegetable kingdom are old unsolved problem in plan t phylogenetics.
On today's palaeontological evidence we know that 250 million years ago, during the Carbonifer ous, t here' lived in co-ex istence trees of gig antic stature, namely the microphyllous Lyc9psid a, t he mac rophyllous P teropsid a and the whorl-leaved Sp haenopsida. Psilophyta, primitive pl an ts in t he ROMAN KOZLOWSKI & PAL GREGUsa Middle Devonian, some 25 million years before the Carboniferous, were much smaller, hardly 0.5 m high, while plants 10 to 12 em and even 1 to 2 cm in height occurred too.
The entirely bare Rh ynia and Hornea, the microphyllous A st er oxyl on, moreover the macrophyllous Protopteridium and Calamophyton, the last wi th its whorled branching, are known to have been contemporaneous.
The general opinion had been t hat the Devonian primitive plants were the sim plest vascular plants and t hat from this common type th ree different groups of the P teridophyta had developed, viz. Lysopsida, Pteropsida and Sphaenopsida. Another opinion, still now prevailing, is that no t only t he Pteridophyta but also the Psilophy ta are r epresen ted by th ree 'pr incipal ty pes and that in turn these plants may have developed from three simpler types whose appearance ma y have occurred in earlier times.
According to W. Zimmermann's "telome theory" the ramification of the Pteridophyta can be traced back to the primitive dichotomy of simple Devonian plants, e.g. the monopodial ramification r esult ed from the outgrowing of one branch of dichotomy ; on the other hand leaves were formed thr ough the flattening of the telome, i.e. the " planati on", while fork-like branching telomes became simple unramified shoot s throug h the reduction of stems. In conformity wi th t he "telome theory" Zimmermann supposes that dichotomy was the primitive branching form and t hat the tw o other branchin g types may have developed ther efrom. Owing to the scarcity of pre-Devonian vascular plant finds, many research workers still consider the P silophyta as the mos t primiti ve vascular plants, and the mosses as their descendants, since fossil mosses ar e known from the Upper Carboniferous only.
These t heories, as well as that of Zimmermann, call for revision on the ba sis of examination of r ecent finds of Ordovician plant r emains made by P ro fessor R. Kozlowski. This discover y is of great importance in so far as it su pplies r eli able ev idence that Ordovician plants were simpler than the Psilophyta. They are namely organisms from 2 to 8 mm high.
Up to now, no such sim ple continental vascular plants have been known.
Aldanophyton described by A. Kryshtofovich from a Middle Cambrian impression is as yet problematic.
The writer's studies of Ordovician plant remains, discovered by Professor Kozlowski, cover complete external and internal mo rphology, the branching types, structure of the vegetative shoot apex, and root apex, r oot hairs, str uctu re and form of the superficial cells of stems, reproductive organs, the archegonium, the an theridium, the sporogonium, the spores, the fe rtile bud and, as far as possible, the internal anatomy in cross and longitudinal sections of stems. The four attached plates illustrate some of these observations. Pla te I sho ws the appearance of these tiny plants
DISCOVERY OF ORDOVICIAN LAND PLANTS 5and their relative sizes. In plates II and III are figured characteristic representatives of the two chief new genera (Musciphyton gen. nov. and Hepaticaephyton gen. nov.). These are supplemented by camera lucida drawings of three species of Musciphyton gen. nov. (pl. IV). The results of the writer's preliminary studies ' may be summarized
__ It has been ascertained that the Cormophyta have lived not only in the Devonian but much earlier too, as early as in the- Ordovician.
These Ordovician plants, being simpler than the Devonian Psilophyta, may summarily be called "Propsilophyta". Plants of this sort were possibly the first vascular plants to have started the vegetation of the Earth's land surface. Their height ranged from one to ten mm. The fact of the existence
at that early period, side by side, of two different types of primitive plants:
monopodial and dichotomous (pl. I, upper and lower rows), is of greatest phylogenetic significance. The writer must, however, confess not having observed complete specimens of both types.
Monopodial type. As is shown by photographs and drawings (pl. IV), the stems of that type were cylindrical and leafless, some without branching, others with monopodial branching. This is proved by the fact that branches of two different thickness were -shot off the same stock (pl. II).
These tiny plants, with or without branching, were highly similar to the taller Devonian Psilophyton, and to setae of our leafy mosses. Their su rface was covered with thick-walled epidermal cells. Stomata had not yet developed. There were vegetative -cones on the shoot apex (pl. II).
Conductive bundles stretched along the middle of stems. Root hairs, in regular arrangement, were developed on subterranean parts (pl. II, fig. 1).
Th e writer has succeeded to differentiate in the studied material some 12-14 specimens of this type on the basis of their external and internal structure. The generic name of Musciphyton gen. nov. is proposed because of their similarity to leafy mosses. A detailed description with the nomenclature of particular forms will be published in the next paper.
Dichotomous type. In this other type the body extends narrowly or widely (pl. I, lower row; also pl. III). The branching is always dichotomous only. These plants were similar to some types of Hepaticae, as well as to the Devonian Taeniocrada, Zosterophyllum and Sciadophyton. Hence they were given the generic name of Hepaticaephyton gen. nov. In the interior of their stem are conductive elements-just as in Psilophyton. The conductive elements have simple pitted walls, indicating that some of these specimens belonged to the sporophyton generation. In some specimens lobes separated from stems, with assimilating hairs on their ends (pl. III).
These specimens may possibly correspond to the prothallium. A detailed description and nomenclature will follow in the next paper.