Fossil cytoplasm is a new research topic of interest in paleobotany. Atomic force microscope （AFM） is a new technology applied widely in physics and biology; however, it is rarely used in paleontology. Here we applied AFM for the first time to study fossil cytoplasm. The results indicate that the fossil cytoplasm is heterogeneous and full of ultrastructures, just like extant cytoplasm, and that the application of AFM, especially in combination with other techniques, can reveal the subcellular details of fossil plants with more confidence.
The diverse clam shrimp Nestoria-Keratestheria fauna is widely distributed in the Dabeigou Formation in northern Hebei and eastern Inner Mongolia of China. Its important component genus Magumbonia from the Dabeigou Formation in the Luanping Basin, northern Hebei, China, is revised on the basis of a scanning electron microscope （SEM） examination of the type species M.jingshangensis Wang, 1984, which revealed morphological features not recognized previously. These include coarse reticulation on the umbo and prominent growth lines ornamented with densely spaced, small tubercles and fine lirae.
LI GangSHEN YanbinLIU YongqingPeter BENGTSONHelmut WILLEMSHiramichi HIRANO
Searching for early angiosperms is a riveting activity in botany because it helps to resolve the phyiogenetic relationships among seed plants and among angiosperms themselves. One of the challenges for this job is what the target fossils look like. Most possibly early angiosperms may elude our scrutiny with gymnospermous appearances. This possibility becomes a reality in a Jurassic plant, Solaranthus gen. nov, which bears a peltaspermalean appearance and enclosed ovules. According to knowledge available hitherto, the latter feature makes it an angiosperm. However, such a feature is more likely to be eclipsed by its gymnospermous appearance. The early age and unexpected character assemblage of Solaranthus urge for a fresh look on the assumed-simple relationship between angiosperms and gymnosperms. Its resemblance to the order Peltaspermales favors the Mostly Male Theory.
Because the cytoplasm of a plant normally degrades after the death of the plant, finding cytoplasm in a plant body after a prolonged period of time, especially in fossil plants, is unexpected. Recent work on several 100-Myr-old plant fossils from Kansas, USA indicates, however, that cells and their contents can be preserved. Most of the cells in these fossil plants appear to be in a state of plasmolysis, and these fossil cells bear a strong resemblance to laboratory-baked cells of extant plant tissues. Based on a comparison with extant material plus biophysical and biochemical analyses of the cytoplasm degrading process, a new hypothesis for cytoplasm preservation in nature is proposed： high temperature, a concomitant of commonly seen wildfires, may preserve cytoplasm in fossil plants. This hypothesis implies that fossilized cytoplasm should be rather common and an appropriate substance for research, unlike previously thought. Research on fossil cytoplasm closely integrates paleobotany with biochemistry, biophysics, as well as fire ecology, and invites inputs from these fields to paleobotany to interpret these provocative findings.
For a long time, paleontologists have been focusing on hard parts of organisms during different geological periods while soft parts are rarely reported. Well-preserved plant cells, if found in fossils, are treated only as a rarity. Recent prowess in research on fossil cytoplasm indicates that plant cytoplasm not only has excellent ultrastructures preserved but also may be a quite commonly seen fossil in strata. However, up to now there is no report of plant cell fossils in China yet. Here plant cell fossils are reported from Huolinhe Coal Mine （the early Cretaceous）, Inner Mongolia, China. The presence of plant cytoplasm fossils in two cones on the same specimen not only provides further support for the recently proposed hypothesis on plant cytoplasm fossilization but also marks the first record of plant cytoplasm fossils in China, which suggests a great research potential in this new area.
The origin of angiosperms has been tantalizing botanists for centuries. Despite the efforts of palaeobotanists, most of the pre-Cretaceous angiosperms are regarded either non-convincing or misdated. The applications of SEM and LM （light microscope） enable us to recognize a coalified fossil plant, Xingxueanthus sinensis gen. et sp. nov., from the Haifanggou Formation （Middle Jurassic, 〉160 Ma） in western Liaoning, China. Xingxueanthus is an ＂inflorescence＂ with more than 20 female units spirally arranged. Each female unit is situated in the axii of a bract. The female unit is composed of an ovule-container and a style-like projection at the top. There is a vertical column bearing several ovules in the ovule-container. The general morphology and the internal structure of Xingxueanthus distinguish itself from any known fossil and extant gymnosperms, and its structures are more comparable to those of angiosperms. Xingxueanthus, if taken as a gymnosperm, would represent a new class, demonstrate an evolutionarily advanced status of ovule-protection in gymnosperms never seen before, and provide new insights into the origin of angiospermy. Alternatively, if taken as an angiosperm, together with Schmeissneria, it would increase the diversity of Jurassic angiosperms, which has been underestimated for a long time, and suggest a much earlier origin of angiospermy than currently accepted.
The fossil record of Progonocimicidae of Hemiptera suborder Coleorrhyncha from China is reviewed. Ovicimex laiyangensis Hong et Wang, 1990, from the Lower Cretaceous of Laiyang, is excluded from Coleorrhyncha. The available generic name Mesocimex Hong, 1983 is resurrected from synonymy and proposed for replacement of the preoccupied name and junior homonym Mesoscytina Hong, 1983, non Mesoscytina Tillyard, 1919. It resulted in following new combinations: Mesocimex abditus (Yu. Popov, 1982) comb. n., Mesocimex ambiguus (Yu. Popov, 1985) comb. n., Mesocimex brunneus (Hong, 1983), comb. n., Mesocimex fidus (Yu. Popov, 1982) comb. n., Mesocimex intermedius (Yu. Popov, 1985) comb. n., Mesocimex kuzbasicus (Yu. Popov, 1985) comb. n., Mesocimex liliputus (Yu. Popov, 1988) comb. n., Mesocimex minutus (Yu. Popov, 1982) comb. n., Mesocimex modestus (Yu. Popov, 1985) comb. n., Mesocimex paulinus (Yu. Popov, 1982) comb. n., Mesocimex cognatus (Yu. Popov, 1982) comb. n. An annotated list of species of Mesocimex is given. In addition, a new species, Mesocimex lini sp. nov., is described based on well-preserved specimens with wings and bodies from the Middle Jurassic of Daohugou, China. This discovery supports the Middle Jurassic age of Daohugou Lagerstatte, since all species of Mesocimex are confined to the Lower-Middle Jurassic. The phylogenetic evolution of Coleorrhyncha is discussed: Cicadocorinae, Karabasiinae, Hoploridiinae, and Peloridiidae are monophyletic clades whereas Progonocimicinae and Karabasidae are clearly paraphyletic groups.
Chuaria is one of the few globally distributed macrofossil pioneers documented in the Precambrian. It is perhaps the most controversial fossil in term of its affinity despite more than one hundred years of study. Many mutually exclusive affinities have been suggested for this frequently encountered fossil. Although often treated as a multicellular alga, this interpretation remains inconclusive because the lacking unambiguous demonstration of cellular structures. In this paper the cellular details of Chuaria are clearly revealed for the first time. The cell walls in Chuaria suggest that it is a multicellular eukaryotic alga, in agreement with the latest biogeochemical analyses. Different thicknesses of cell walls suggest primary cellular differentiation in this organism. Membrane-like structures within the cells (the first to be reported in Precambrian fossils) imply a eukaryotic nature. This study partially resolves the century-long controversy over the affinity of Chuaria, and makes Chuaria one of the few recognized multicellular eukaryotes before the Neoproterozoic glaciation.
WANG XinYUAN XunLaiZHOU ChuanMingDU KaiHeGONG Miao
