A Fossilized Microcenosis in Triassic Amber
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J Eukaqlnr. Micmbrol., 46(6), 1999 pp. 571-584 0 1999 by the Society of Protozoologists A Fossilized Microcenosis in Triassic Amber WILFRIED SCHONBORN,a HEINRICH DORFELT? WILHELM FOISSNER,’ LOTHAR KRIENITZd and URSULA SCHAFER” “Friedrich-Schiller-UniversitatJena, Institut fur Okologie, Arbeitsgruppe Limnologie, Winzerlaer StraJe 10, 0-0774.5 Jena, Germany, and bFriedrich-Schiller-Univer.sitatJenn,lnstitut fiir Ernahrung und Umwelt, Lehrgebiet Lnndschaftsokologie und Naturschutz, DornburgerslraJe 159, 0-07743 Jena, Germany, and ‘Universitut Salzburg, Institut fur Zoologie, HellbrunnerstraJe 34, A-5020 Salzburg, Austria, and dInstitut fur Gewasseriikologie und Binnenjscherei, Alte Fischerhiitte 2, 0-16775 Neuglobsow, Germany ABSTRACT. Detailed data on bacterial and protistan microfossils are presented from a 0.003 mm3 piece of Triassic amber (Schlier- seerit, Upper Triassic period, 220-230 million years old). This microcenosis, which actually existed as such within a very small, probably semiaquatic habitat, included the remains of about two bacteria species, four fungi (Palaeodikaryomyces baueri, Pithomyces-like conidia, capillitium-like hyphae, yeast cells) two euglenoids, two chlamydomonas (Chlamydomonas sp., Chloromonas sp.), two coccal green microalgae (Chlorellu sp., Chorzcystis-like cells), one zooflagellate, three testate amoebae (Centropyxis aculeata var. oblonga-like, Cyclopyxis eurystoma-like, Hyalosphenia baueri n. sp.), seven ciliates (Pseudoplatyophrya nana-like, Mykophagophrys rerricola-like, Cvrtolophosis mucicola-like, Paracondylostoma sp.. Bryometopus triquetrus-like, Tetrahymena rostrata-like, Paramecium triassicum n. sp.) The microfossils correspond to or diverge from extant species only slightly. Key Words. Evolutionary comments, fossilized bacteria, ciliates, flagellates, fungi, green algae, testaceans, preservation, Schlierseerit. HE “Schlierseerit”, amber which comes from layers of An amber piece containing microfossils was placed in the T Raibler Sandstone of the “Leitnernase” near the village chamber, covered with a cover glass, and sealed by phytohistol of Schliersee (Bavaria, Germany), has been investigated inten- (Carl Roth GmbH & Co., Karlsruhe, Germany). sively for 10 years by many scientists. This amber dates from A Zeiss-Microscop Axioplan equipped with differential in- the Upper Triassic period (Carnian stage of Keuper) and may terference contrast and a throughlight-stereoscopic picture mi- be 220-230 million years old. Its finder, U. Ch. Bauer, discov- croscope Axiolab (up to lOOOX enlargement without restriction ered the amber as small pieces of < 1 mm to max. 20 mm. A of resolution) were used to observe the inclusions tridimen- summary of all findings concerning this amber has been com- sionally . piled by Vavra (1996; see also Nickel 1995). Using carbon-13- nuclear magnetic resonance spectra, the resin source is probably RESULTS a coniferous plant of the Araucariaceae (Lambert, Johnson, and Fungi (Fig. 1-7) Poinar 1996), already known from the Palaeozoic period. The Many fungal remnants were included in the amber between preliminary investigation on this amber was carried out by remains of plants, bacteria, and protists. Five types of fungi Poinar, Waggoner, and Bauer (1994; see also Bauer 1993) who were regularly observed: described bacteria, fungi, algae, testaceans, and ciliates. Since there are only scant findings of freshwater (or terrestrial) pro- 1. Pulueodikuryomyces buueri-like Dorfelt, already described tists from early geological periods, the above-mentioned are the from the Schlierseerit (Dorfelt and Schiifer 1998), could be earliest known soft-bodied forms. The present paper describes newly confirmed. It is a saprophytic fungus with non-septate in more detail a microcenosis of an amber fragment with a hyphae and vesiculi, developing septae, branches at the ves- volume of only 0.003 mm3,and comments on evolutionary and iculi, great clamps or loops, and cysts at the loops (Fig. 1, ecological consequences of these discoveries. 2, 3). 2. A saprophytic fungus with septate hyphae and oogonia-like METHODS cysts, possibly a stage from Palaeodikuryomyces baueri-like The size of the pieces of Schlierseerit exploited in the present (Fig. 4) or an as yet undescribed saprophytic fungus. paper ranges from nearly 100 pm to some mm. Since the mi- 3. Thick-walled, capillitium-like hyphae with papillary orna- crofossils are situated tridimensionally in the amber, simple mi- ments and occasionally with blastoconidia (Fig. 5), probably croscopic observation and taking micrographs is difficult; usu- an as yet undescribed species. ally the distance between object and lens is too large. Sections 4. Remnants from a saprophytic fungus, which may be a yeast are impossible because many inclusions would be destroyed. cell of a dimorphic fungus or a separated visicle from Pu- Breaking it into smaller pieces is the best method because the lueodicuryomyces buueri, germinating with small hyphae inclusions remain undamaged and are eventually set free from (Fig. 6). the amber. 5. Pithomyces-like conidia, dark brown, muriform (Fig. 7), Tiny or broken amber pieces were at first investigated in may be macroconidia belonging to the capillitium-like hy- water, photographed, and after air drying, treated with a neutral phae described above. mixture of paraffin oil and alkylaromates (Chemisches Labor Bacteria (Fig. 8, 9) Carl Zeiss, Oberkochen, Germany); the density (1.525) of this mixture is similar to that of the Schlierseerit. The oil penetrates We found many filamentous and single bacterial structures the amber and microfossils, especially fungal hyphae, and (Fig. 8, 9), but it is impossible to identify them without chem- clears the structures, but only in the first 30-60 min, which is ical analysis. the most favorable time for microscopic investigations. After Algae (Fig. 10-17) 60 min the oil dissolves the amber and destroys the pieces. For preservation, small chambers (“sarcophages”) were Euglenoids. Two specimens of euglenoid flagellates were burned with the help of CO, laser in glass microscope slides. found in the Triassic amber. One cell body was spirally twisted, indicating the typical metabolic character of Euglena cells (Fig. 10). The cell was approximately 25 p,m long (unfortunately, the Corresponding Author: W. Schonborn-Telephone number: 0049/ apical part was covered and hence not clearly visible), width 03641/657591; FAX number: 0049/03641/657600; Email: varied between 2-6 pm. The cell had a short caudal spine. limnolog @rz.uni-jena.de Inside the cell, different granulated and refractile structures 57 1 572 J. EUKARYOT. MICROBIOL., VOL. 46, NO. 6, NOVEMBER-DECEMBER 1999 Fig. 1-2. Palaeodikaryornyces baueri. a, clamps or loops; b, cysts, growing from the clamps; d, vesicles. Fig. 1, bar 5 Fm; 2, bar 20 pm. were visible, possibly chromatophores, paramylon grains, vac- sembling extant Chlorella species (Fig. 12, 16), and slightly uoles, and reddish carotene-containing oil droplets. The other ellipsoidal cells resembling extant Choricystis-like cells because cell, about 50 X 12 pm in size, exhibited a fusiform shape (Fig. they contained trough-like parietal chloroplasts. The cells at the 11). lower region of the size spectrum (< 3 pm) were identified as Monadal chlorophytes. There were two types of ovoidal “picoplankton” (Fig. 15, 17). chlorophytes in the amber. The thick-walled cells clearly indi- cate the character of monodal algae, although flagella were Zooflagellates (Fig. 18-20) missing. The cells were oval in longitudinal view, and spherical About ten inclusions resembled longish cells with a thread- in the apical view. The first type of cells (Fig. 11) had a size like elongation on one end, very likely a flagellum. The length of 4-6 X 8-10 pm. It contained a cup-shape chloroplast ranged from 9.613.0 pm (including flagellum). Zoochlorellae equipped with a pyrenoid in the basal part. These cells can be were not visible, so these inclusions were very likely heterotro- identified as the genus Chlamydomonas. The second type of phic flagellates. cells had a size of about 15-18 X 28-32 p,m. The inner side of the cell wall was covered by a chloroplast, which did not Testate Amoebae (Fig. 21-27) contain a pyrenoid. In the central part of the cells several vac- uoles were visible. A reddish-colored, stigma-like structure was Three testacean species could be identified. found near the apical region in some cells. These cells are com- parable with extant species of the chlamydophycean genus 1. Hyalosphenia baueri n. sp. (Fig. 21, 22) Chloromonas (Fig. 11-15). Diagnosis. Shell about 60.0 X 95.5 pm, indistinctly vase- Chlorococcal picoplankton. Wide areas of amber were shaped, with two opposite lateral pores, membraneous, struc- filled with minute spherical structures. In most cases, these tureless, brown, compressed, with a small collar around the ap- might be artifacts. However, some specimens showed the char- erture, which is terminal and (probably) oval. acter of algal cells, containing chloroplasts and vacuoles. We Type location. Triassic amber from Mount Leitnernase near classified these small structures, with a size of 2-5 X 3-6 pm, the village of Schliersee (Bavaria, Germany). in two different morphotypes: more or less spherical cells re- Type material. Holotype (Fig. 22) SCHONBORN ET AL.-FOSSILIZED MICROCENOSIS IN TRIASSIC AMBER 573 Fig. 3-7. Palaettdikatyomyces baueri, and other fungal remnants. 3. Palaeodikuryomyces baueri. hyphae; a, clamps or loops; c, rounded apiculus of the hyphae; d, vesicles.