Possible fossil Sporae dispersae of Hepaticae and Anthocerotales in the fossil record Divya Darshan Pant & Rita Singh Pant, Divya Darshan & Singh. Rita 1991. Possible fossil Sporae dispersaeof Hepaticae and Anthocerotales in the fossil record Palaeobotanist 39 (1) : 20- 36 The paper attemr:s to find the characters which can distinguish the spores of Hepaticae and Anthocerotales from iso- or micro-~pores of pteridophytes and pollen grains of gymnosperms and angiosperms for the indentification of possible fossil Sporae dispersae of bryophytes reported from different geological horizons. The problem was approached by looking for characters in fossil spores which are (i) exclusively bryophytic, (ii) prevailingly bryophytic, and (iii) closely matching characters of in situ spores of fossil bryophytes in a first hand comparison. Our account also takes into consideration the Sporae dispersae which were described or suspected by previous workers as those of bryophytes but which could equally well belong to pteridophytes. Key-wor-ds- Palynology, Adherent tetrads, Pseudocolpus, Hepaticae, Anthocerotales. Divya Darshan Pant & Rita Singh, Department of Botany, University of Allahabad, Allahabad 211 002, India. '~n:hT ~ ~ 1f'41~(\hfl ~~ ~ ~ ~"1f(f * ~ <r!l'f;r 'Ri ~ fhrr ~ ~ ~ ~rrpif nrmu-trJf if ;j.f F<PW ~ q;1- <iJT;;R 'liT )f!l'ffi fu;m Tf'llT %~ 3lTun: 1i< 1f"'llfli<JtRl <f; <tT ~ ~ ~ ~ ~ ~ ~ ~ t{\i1'f'I$t)41 <f; ~3iT ,PIT :>i'1I~d"l"t"1"t Gltif <f; it <tT "IT wfl It it ~ ~~ ~ ~3iT ~ ~ ~I ~ ~ ~3iT ~u Gltif <f; aITrlfd' <f; 3!f\!f.fuhur if ;m- t<! if ~ <;l1414iI$t)~1 ~3iT ~~ ~?: ~ (i)~' ~ ~~, ~~, Ilfuct' fu;it (ii) a'!T (iii) <f; Bfl''lT't it ~ ~-~ ~ ~ ~ ~ ~ ~3iT ~ ~ <tT if fu;m Tf'llT %1 'mU-trJf if;j.f 'liT \ft 3f!Jl'lR Tf'llT % f<;; ~itu-'l'nT3iT it 'll1~jqo;l$tl41 'liT qfUfd' fu;m % 3f'lfiU ~ G!f'fd' fu;m %<9m it t{\il4iI~t)41 <f; ~ ~ wRt ?:I AFTER the discovery of hepatic thalli in British stalked sporangia had arisen from a common thallus. Carboniferous rocks (Walton, 1925, 1928), the time Dixon (1927) has referred this fossil to Andreaea. As range of this group was further extended up to the the spores in the spore sacs are not accompanied by Devonian by Hueber (1961) who reported elaters, the attribution of this fossil to Hepaticae Hepaticites devonicus from Onteroa Red Beds of becomes doubtful (see Krassilov & Schuster, 1984). North America which is now renamed as Schuster (1966) has accordingly referred the genus Pallavicinites devonicus (Hueb.) Schuster (see to an order of its own, the Sporogonitales. Schuster, 1966). There are also a few problematic Another fossil of the same kind called fossils which have been reported from the Lower Lyonophyton was described by Remy and Remy Devonian. One of these was referred by Andrews (1980) from. Rhynie Chert bed as haVing as (1960) ro Sporogonites Halle and it shows a thallus­ "independent and possibly autotrophic gametophyte like carbonaceous mass below a number of parallel which is of approximately equal size and shape with subadjacent, unbranched erect stalks. If unbroken the sporophytes from the same beds" This fossil is they terminate in ovoid spore sacs containing spores described as haVing a cup-shaped gametophore with ca 20-25 J.Lm in diameter. No details of the spore lobed margins. Remy and Remy (1980) have characters are available. Andrews believed that the compared it with Horneophyton on the basis of itS 20 PANT & SINGH-FOSSIL SPORAE DISPERSAE OF HEPATICAE AND ANTHOCEROTAlES 21 anatomy as well as the morphology of fertile parts the environment was transitional between that of and they have further suggested that Lyonophyton water and terrestrial plants and the plant shows a rhyniensis seems to be "the gametophyte of a plant combination of characters of both the habitats. He representing an evolutionary stage previous to the further suggests that Protosalvinia was probably separation of land plants into bryophytes and higher "caught in act" of evolving into a plant which was land plants." Till recently all other Devonian forms becoming adapted for living in a desiccating which had a central strand were included among the envi ronment. pteridophytes. In fact, one of these called, Rhynia Parka decipiens is another Lower Devonian major was regarded as one of the best known plant haVing a flat thallus-like body whose surface Devonian pteridophytes but a recent renaming of was covered by flattened disc-shaped structures with this form as Aglaophyton by Edwards (1986) is based numerous cutinized spores ca 28-34 /-.Lm in diameter. on his claim that its central strand lacks secondary The thallus is parenchymatous in nature (Lang, wall thickenings in the longitudinal cell walls. 1937). The affinites of Parka too are uncertain, it has According to him it consists of cells having an alga-like thalloid body and cutinized spores like uniformly thick walls and he raises doubts about its those of land plants (see Walton, 1953). being a vascular plant suggesting that it had a The third uncertain fossil Steganotheca shows a bryophytic level of organisation (Taylor, 1988). plant compression which is comparable with However, the observations of Edwards, on this form, Cooksonia in having terminal sporangia on which is otherwise quite like Cooksonia and Rhynia dichotomously branched axes but their central gwynne vaughanii need confirmation before they strands lack tracheids so that it could be compared can be accepted particularly when they are based on with bryophytes instead of pteridophytes. the negative evidence of thickenings. The above reports of megafossils beginning Beside the above two forms, there are some with Lower Devonian make it at once likely that other uncertain Devonian bryophyte-like genera, some of the dispersed miospores described by called Protosalvinia Dawson, Parka decipiens Lang different authors from the beds of different and Steganotheca. Out of these, Protosalvinia is geological ages beginning with strata of this period reported from the Upper Devonian Black Shales of could even belong to bryophytes. Indeed, after east-central U.S.A. and its detached sporiferous Walton discovered undoubted structurally preserved organs usually show once forked branches which are bryophytes in the Carboniferous, he suggested to approximately 2-5 mm in width and appear to have Knox (1939) that she should look for spores of been borne on a thalloid plant body. The forks of bryophytes among fossil Sporae dispersae. However, the thallus show sporocarp-Iike structures, each she only mentioned some fossil spores (see Knox, containing a single tetrad of 4 large spores (? 1939; figs 41-51) which were broadly comparable megaspores) ca 200 /-.Lm in the cavity of inner tissues. with those of some liVing bryophytes like Anthoceros The affinities of Protosalvinia are uncertain. It has chilensis, Moerckia hibernica, Anthoceros punctatus, been assigned to the algae by White and Riccia crystallina, R. beyrichiana, R. jluitans, Stadnichenko (1923) but Kidston and Lang (1924) Fossombronia angulosa and Plagiochasma subplana. believed it to be intermediate between the algae and To the best of our knowledge the next paper lowermost vascular plants. Krausel (1941) created a dealing with bryophytic spores was published by new intermediate class, the Algomycetes, between Lundblad (1954) when she created a new form algae and fungi. Arnold (1954) observed that "it had genus based on the dispersed united spore tetrads evolved to a level comparable to that of the Ricciisporites tuberculatus Lundb lad from the bryophytes" but at the same time he contradicted Jurassic of Scania and attributed them to Ricciaceae himself by saying that there was no apparent reason but later thought that its affinity was dubious for classifying it with the bryophytes. Lacey (1969) (Lundblad, 1959). Krassilov and Schuster (1984) find thought that Protosalvinia could be compared with that R. tuberculatus can be compared with a Riccia-Iike bryophytes which were reported by sphaerocarpalean tetrad more closely. Walton (1949) and Hueber (1961) from the In her account of Upper Mesozoic microfloras Carboniferous but sporogonia of Riccia differ from from south-eastern Australia, Dettmann (1963) those of Protosalvinia in having a number of tetrads compared some fossil miospores with those ofsome of smaller spores instead of a single one of large extant and fossil bryophytes, e.g., Foraminisporis spores. Stewart (1983) is of the opinion that dailyi (Cookson & Dettmann) Dettmann has been Protosalvinia does not fit well into any group of compared with the spores of Phaeoceros extant plants. The shales in which Protosalvinia has bulbiculosus (Brotero) Prosk., Foraminisporis been found suggest a shoreline (littoral zone) where wonthaggiensis (Cookson & Dettmann) Dettmann 22 THE PALAEOBOTANIST with spores of NOLOthyLas breutelLi Gottsche, of the spores of some liVing forms of Indian Rouseisporites retieuLatus Pocock, with spores of Hepaticae and Anthocerotales as well as published Riceia beyrichiana Hampe and R eanaLicuLata Hoff. accounts of spores of the eX'1ant members of these and Couperisporites labuLallis Dettmann with spores groups besides looking for possible bryophytic of Naiadita LaneeoLala Buckman as described by spores in published literature of fossil Sporae Harris (1939). Among Other Sporae dispersae, Meh ra dispersae. As a result we can categorically state that (1974) compared some spores described as colpate and porate pollen grains (microspores) of Leisphosphaera rOlunda, Uniporata torosa, living gymnosperms and angiosperms