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111
ISSN 0031-0301, Paleontological Journal, 2021, Vol. 55, No. 1, pp. 111–115. © Pleiades Publishing, Ltd., 2021.
Russian Text © The Author(s), 2021, published in Paleontologicheskii Zhurnal, 2021, No. 1, pp. 114–116.
New Findings of Microfossils in the Orgueil Meteorite
A. Yu. Rozanov
a, b, d
, R. B. Hoover
c
, A. K. Ryumin
b,
*, E. A. Saprykin
b, d
,
M. I. Kapralov
b, d,
**, and A. N. Afanasyeva
b
aBorissiak Paleontological Institute, Russian Academy of Sciences, Moscow, 117647 Russia
bJoint Institute for Nuclear Research, Dubna, Moscow oblast, 141980 Russia
cU.S. Space & Rocket Center, Huntsville, Alabama, United States
dDubna State University, Dubna, Moscow oblast, 141982 Russia
*e-mail: arjumin@mail.ru
**e-mail: mast34@mail.ru
Received December 9, 2019; revised July 15, 2020; accepted July 15, 2020
Abstract—The Orgueil meteorite was studied using a TESCAN VEGA 3 scanning electron microscope. As a
result, new microfossils were found, including a fragment of a pennate diatom shell, tubular structures with
double porous cell walls (prasinophytes?), hollow spheres with a process (acritarchs?), and spore-like struc-
tures. The problem of the cometary origin of the Orgueil meteorite is discussed.
Keywords: Orgueil meteorite, carbonaceous chondrites, microfossils, prasinophytes, diatoms, acritarchs
DOI: 10.1134/S0031030121010111
INTRODUCTION
The micropaleontological study of the Orgueil
meteorite goes back into 1961, when first biogenic
hydrocarbons (Nagy et al., 1961) and later, micro-
structures (so-called “organized elements”), indige-
nous to the meteorite and similar in morphology to
fossil algae, were discovered in the meteorite (Claus
and Nagy, 1961). Staplin (1962) found organic
remains, including microfossils of unknown system-
atic position, contaminants, and Cretaceous micro-
fossils. Palik (1962) recognized filamentous struc-
tures, similar in morphology to algae in the Orgueil
meteorite. It was concluded (VanLandingham, 1965;
VanLandingham et al., 1967), that the organized ele-
ments are sufficiently structured and most likely can-
not be considered contaminants. Rossignol-Strick
and Barghoorn (1971) recognized different structures
in the Orgueil meteorite (hollow spheres, membranes,
funnel-shaped ones, etc.).
Since the mid-1990s, different fossilized bacteria
and protists were found in the Orgueil meteorite using
micropaleontological studies (Gerasimenko et al.,
1999; Hoover, 2006a, 2006b; Hoover and Rozanov,
2005; Hoover et al., 1998, 2004, 2008, 2018; Rozanov,
1996, 2009; Zhmur et al., 1997).
DESCRIPTION OF MICROFOSSILS
Several interesting findings have recently been
made in the Orgueil meteorite at the Astrobiology
Sector of Laboratory of Radiation Biology of the Joint
Institute for Nuclear Research (JINR, Dubna, Rus-
sia) using a TESCAN VEGA 3 scanning electron
microscope.
Tubular structures (Plate 13, figs. 1, 2; see inset)
form colonies: inner cavities are 5–10 μm, wall thick-
ness is 2–4 μm. The wall is double-layered, penetrated
by radial channels. Based on morphological features,
one can suggest that these structures belong to prasin-
ophytes.
Spheres with a process. A single ~19 μm sphere is
hollow, partially destroyed (Plate 13, fig. 3). A thick
wall without pores (about 2–2.5 μm thick), slightly
curved, forming a process (P1). The cavity was
incrusted with magnetite crystals. A smaller ~5 μm
sphere (Pl. 13, fig. 4) is well preserved, with a short
process (P2). These findings supposedly belong to
acritarchs.
A frustule fragment of a p ennate diatom o f a d umb-
bell shape is present. Its width at its narrow part is
5.3 μm; in the widest part is 5.8 μm. The length of the
preserved fragment is about 14 μm. The frustule’s total
length could be about 20 μm (Plate 13, fig. 5).
Sacculate structures (8–12 μm in size) are similar
to spores of algae and fungi; they resemble spores of
bryophytes in some cases. Some structures have
suture-like grooves (Plate 13, fig. 6; Plate 14, fig. 1; see
inset); one of them is represented by a framboid devel-
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PALEONTOLOGICAL JOURNAL Vol. 55 No. 1 2021
ROZANOV et al.
5 µm 20 µm
5 µm
2 µm
2 µm
5 µm
P1
P2
1
3
5 6
4
2
Plate 13
PALEONTOLOGICAL JOURNAL Vol. 55 No. 1 2021
NEW FINDINGS OF MICROFOSSILS IN THE ORGUEIL METEORITE 113
Explanation of Plate 14
Fig. 1. Magnetite framboid = (after a spore-like structure); Orgueil meteorite, JINR, spec. 1/2.
Figs. 2–4. Spore-like structures with pits; Orgueil meteorite, JINR, spec. 1/2.
2 µm2 µm
5 µm
5 µm
1
34
2
Plate 14
Explanation of Plate 13
Fig. 1. Tubular structure (supposed prasinophyte) with double porous cell wall, penetrated by radial canals; Orgueil meteorite,
JINR, spec. 1/9.
Fig. 2. Colony of (supposed) prasinophytes; Orgueil meteorite, JINR, spec. 1/9.
Fig. 3. Wall fragment of a ~19 μm hollow sphere (supposed acritarch); shell wall is slightly curved, forming a process (P1); wall
thickness is about 2–2.5 μm; this sphere was initially incrusted by magnetite crystals; Orgueil meteorite, JINR, spec. 1/7.
Fig. 4. Different-sized spheres (0.5–3 μm) and a ~5 μm large sphere with a short process (P2) (supposed acritarch); Orgueil mete-
orite, JINR, spec. 1/7.
Fig. 5. Frustule fragment of pennate diatom; Orgueil meteorite, JINR, spec. 1/7.
Fig. 6. Spore-like sacculate structure with suture-like grooves; Orgueil meteorite, JINR, spec. 1/2.
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PALEONTOLOGICAL JOURNAL Vol. 55 No. 1 2021
ROZANOV et al.
oped after a spore-like form (Plate 13, fig. 6). Other
specimens have pits (Plate 14, figs. 2–4).
ORIGIN
OF THE ORGUEIL METEORITE
Due to a wide variety of findings, it is worth dwell-
ing in more detail on the Orgueil meteorite’s origin.
All meteorites were believed to come from the main
asteroid belt or the Oort Cloud. However, recent dis-
coveries suggest that comets may be the most likely
parent bodies of CI1 and possibly CM2 carbonaceous
chondrites.
The Orgueil meteorite (like other CI1 meteorites)
has distinct liquid water traces affecting its mineral
matrix. This is strong evidence for the presence of liq-
uid water in its parent body. It was also noted that the
D/H isotope ratio in the Orgueil meteorite is close to
that in the comet 103P/Hatley 2. All the above and the
similarity between indigenous amino acids and amines
found in the Orgueil meteorite and those in comets
serve as a solid argument in favor of its cometary origin
(Hartogh et al., 2011; Wickramasinghe et al., 2012).
Based on accounts of witnesses of the Orgueil
meteorite fall, its trajectory entering the atmosphere
and the orbit were calculated. The orbital parameters
(perihelion and aphelion) indicate that a meteorite
parent body could have originated either from the
Apollo group of water-bearing asteroids or from the
Jupiter-family or the Halley-type comets.
Studies have shown that the Orgueil meteorite is
significantly heterogeneous in its mineral composi-
tion; different parts of the meteorite are of varying ori-
gin and vary considerably in their age. Based on the
above arguments in favor of the cometary origin of the
Orgueil meteorite, the following model of its forma-
tion seems probable: the presolar interstellar and
intergalactic micrometeorite matter, along with vola-
tiles and water ice, condensed on a cometary parent
body, forming the inner core of the future meteorite.
During the meteorite accretion, a micrometeorite
matter appeared during different events, such as aster-
oid collisions, impact events on planets and moons,
tails of other comets, etc. overgrew its core.
Comets are known to lose a significant amount of
their matter each time they pass the perihelion. Some
part of this matter is believed to enter the Earth’s
atmosphere as meteorites. Observations show the pos-
sibility of the presence on most comets of conditions
favorable for, at least, the preservation of various
extremophilic microorganisms, or even their complete
metabolism. When a meteorite enters the atmosphere,
only its outer layers are heated, while the temperature
of the inner layers remains stable (Wickramasinghe
et al., 2012).
CONCLUSIONS
Thus, the hypothesis of the cometary origin of the
Orgueil meteorite seems quite probable. It can also
serve as a justification for the presence of indigenous
objects morphologically similar to microfossils in the
meteorite.
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Translated by D. Voroshchuk