''Beorn leggi'' is an extinct species of
tardigrade
Tardigrades (), known colloquially as water bears or moss piglets, are a phylum of eight-legged segmented micro-animals. They were first described by the German zoologist Johann August Ephraim Goeze in 1773, who called them Kleiner Wasserbä ...
s, and the known first fossil tardigrade, discovered and described in 1964 from
Late Cretaceous
The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', ...
amber
Amber is fossilized tree resin that has been appreciated for its color and natural beauty since Neolithic times. Much valued from antiquity to the present as a gemstone, amber is made into a variety of decorative objects."Amber" (2004). In ...
from
Manitoba
, image_map = Manitoba in Canada 2.svg
, map_alt = Map showing Manitoba's location in the centre of Southern Canada
, Label_map = yes
, coordinates =
, capital = Winn ...
,
Canada
Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...
. It is the only species in the genus ''Beorn'', and family Beornidae.
It is one of two fossil tardigrades known from the
Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...
, the other being ''
Milnesium swolenskyi'' from the Turonian
New Jersey amber
New Jersey Amber, sometimes called Raritan amber, is amber found in the Raritan and Magothy Formations of the Central Atlantic (Eastern) coast of the United States. It is dated to the Late Cretaceous, Turonian age, based on pollen analysis of t ...
In addition to some other finds from the
Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...
and the
Cambrian period, Beorn is one of the few references to the existence of tardigrades in the history of the
earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...
, and its largely modern appearance shows that tardigrades must have diversified considerably before this time.
The species was first described in 1964 by Kenneth W. Cooper, the typological specimen is now in the Museum of Comparative Zoology at
Harvard University
Harvard University is a private Ivy League research university in Cambridge, Massachusetts. Founded in 1636 as Harvard College and named for its first benefactor, the Puritan clergyman John Harvard, it is the oldest institution of high ...
. The generic name ''Beorn'' was chosen by Cooper in reference to a figure of the same name from the children's book
The Hobbit
''The Hobbit, or There and Back Again'' is a children's fantasy novel by English author J. R. R. Tolkien. It was published in 1937 to wide critical acclaim, being nominated for the Carnegie Medal and awarded a prize from the ''N ...
by
J. R. R. Tolkien
John Ronald Reuel Tolkien (, ; 3 January 1892 – 2 September 1973) was an English writer and philologist. He was the author of the high fantasy works ''The Hobbit'' and ''The Lord of the Rings''.
From 1925 to 1945, Tolkien was the Rawlins ...
, which can occur both in the shape of a man and that of a bear. The specific name ''leggi'' goes back to the student William M. Legg, who in the summer of 1940 created a larger collection of amber, in which also the tardigrade copy was found. He died in 1953 before finishing his thesis at
Princeton University
Princeton University is a private research university in Princeton, New Jersey. Founded in 1746 in Elizabeth as the College of New Jersey, Princeton is the fourth-oldest institution of higher education in the United States and one of the ...
. Cooper, his friend and scientific mentor, named ''Beorn leggi'' after him.
Characteristics
The only known individual is enclosed in honey-colored amber, the length, width and height of which are given as 7, 6 and 3 millimeters. The animal itself is 0.3 millimeters long and 0.08 millimeters wide; As is the case with modern tardigrades, the cylindrical body is flattened on the ventral side.
The cuticle is smooth, slightly thickened on the backside, but does not harden to platelets (sclerites), so that ''Beorn'' is one of the "naked" tardigrades. A total of four furrows extend transversely to the longitudinal axis of the body (transversally) around the whole body, which divide these superficially into five regions:
*The first or prostomial region forms the head on which there are no structures, such as filiform cirri or clavicles, which are used in some modern modes of sensory perception; Even
eyes
Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and con ...
can not be identified. The
mouth environment is inconspicuous and apparently does not have warren-like projections (papillae).
*The second region is the first fuselage segment, where the first pair of
legs are located. On the back is a short transverse furrow, which is slightly displaced towards the back, opposite the center line of the segment.
*The third and fourth regions bear the second and third pairs of legs. Here, too, there are shorter transverse furrows on the back, which run out laterally to the leg shoulder. They are, however, shifted forward against the center line of the segment.
*In the fifth region there is a transverse furrow on the
abdomen
The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the to ...
, which runs out slightly laterally on the back line.
The length ratio of the segments 2 to 5 is indicated as 1: 1.3: 1.3: 2.
The legs are presumably telescopically retracted and each carry four unequally long claws arranged asymmetrically with respect to the middle of the leg. Other features, such as the structure of the stiletto apparatus or the mucous musculature, can not be recognized; Also the position of the sex opening (gonopore) with respect to the anus, which could have given further indications of the class belonging to the species, can not be ascertained.
Habitat
The origin of the present amber specimen is unknown; It was part of secondary sediment deposits on the lake shore of
Cedar Lake, not far from the
Saskatchewan River
The Saskatchewan River (Cree: ''kisiskāciwani-sīpiy'', "swift flowing river") is a major river in Canada. It stretches about from where it is formed by the joining together of the North Saskatchewan and South Saskatchewan Rivers to Lake Winn ...
outlet and southeast of The Pas town in the Canadian province of
Manitoba
, image_map = Manitoba in Canada 2.svg
, map_alt = Map showing Manitoba's location in the centre of Southern Canada
, Label_map = yes
, coordinates =
, capital = Winn ...
. Observations suggest that the habitat of Beorn leggi was a swamp-like wetland biotope.
Classification
The affiliation of ''Beorn leggi'' to the tardigrades may be considered assured; Moreover, the species can even be assigned to one of the three modern classes - the absence of head structures such as Cirri and Clavae and back armorings suggests a division into the Eutardigrada. Within this class, ''Beorn leggi'' is placed in a separate family Beornidae, which however has to be regarded as a pure form taxon. However, other studies have subsequently interpreted it as having affinities with
Hypsibiidae
The Hypsibiidae are a family of water bears or moss piglets, tardigrades in the class Eutardigrada.
Subfamilies and genera
* Subfamily Diphasconinae
** '' Diphascon''
** '' Hebesuncus''
** '' Paradiphascon''
* Subfamily Hypsibiinae
** '' Acu ...
.
Accompanying finds
Together with ''Beorn leggi'', a young animal has been found which is only very poorly preserved, so that hardly any statements regarding its specific characteristics are possible beyond the identification as a bearded animal. Because two hard-to-recognize structures at or near the head can be interpreted as Cirrus and Clava, it is sometimes viewed as part of the
heterotardigrada
The class Heterotardigrada includes tardigrades (water bears) that have cephalic appendages and legs with four separate but similar digits or claws on each. 444 species have been described.
Anatomy
The anatomy of the reproductive system is an ...
; However, this identification can not be considered as secured. There is probably no close relationship with ''Beorn leggi''.
[K. W. Cooper: The first fossil tardigrade „Beorn leggi“, from Cretaceous Amber. in: Psyche – a Journal of Entomology. Lexington Mass 71.1964,2, S. 41. ISSN 0033-2615]
References
{{Taxonbar, from1=Q818582, from2=Q18520266, from3=Q20020090
Parachaela
Tardigrade genera
†Beorn (tardigrade)
Fossil taxa described in 1964
Campanian genera
Canadian amber
Organisms named after Tolkien and his works