Triassic deposits are widespread
in Northern China, but Tetrapod fossil producing locations are very rare. Those
that are known are restricted to the Heshanggou, Ermaying and Tongchuan
formations, with the Ermaying producing the most abundant and diverse
assemblages.
In a paper published in the
journal Vertebrata PalAsiatica on 12 January 2015, Liu Jun of the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences describes a series of Kannemeyeriiforme Dicynodont remains from two
new Triassic localities in Liulin and Linxian counties in Shanxi Province.
The first set of remains comprise
the front part of a skull with an associated jawbone, a cervical vertebra, a
rib, a left humerus, radius, femur and tibia and an incomplete right ilium from
an exposure of the Tongchuan Formation at Baidaoyu in Linxian County. These
remains are placed in the genus Sinokannemeyeria,
due to the wide low shape of the skull, the short anterior end of the
premaxilla, a shallow depression on the anterior of the premaxilla, long
dentary symphysis and a wide femur, and described as a new species, Sinokannemeyeria baidaoyuensis, meaning
‘from Baidaoyu’, due to an extension of the prefrontal bone level with the
posterior margin (back) of the postnarial excavation.
Sinokannemeyeria baidaoyuensis:
Skull in dorsal (A), ventral (B), anterior (C), and lateral (D) views; lower
jaws in dorsal (E), lateral (F) and ventral (G) views. Abbreviations: L,
lacrimal; M, maxilla; N, nasal; Pf, prefrontal; Pm, premaxilla; Sm,
septomaxilla. Lui (2015).
Lui also notes that the
caniniform tooth of the specimen is not completely wrapped by the caniniform
process, and that this does not appear to be as a result of post-mortem damage.
Since this state would weaken the tooth and has no apparent useful function it
is thought to be a pathology suffered by the animal in life. The specimen also
has weakly sutured skull bones and poorly ossifies ends on the humerus and femur,
which may indicate it was a sub-adult.
Sinokannemeyeria baidaoyuensis:
(A) A cervical vertebra in anterior view; (B) distal portion of left humerus in
ventral (B1) and dorsal (B2) views; (C) left radius in anterior (C1) and
posterior (C2) views; D. partially right ilium in lateral (D1) and medial (D2) views;
(E) left femur in posteroventral (E1) and anterodorsal (E2) views; (F) left
tibia in proximal (F1), anterior (F2) and posterior (F3) views. Abbreviations: cn.c,
cnemial crest; ect, ectepicondyle; ent, entepicondyle; ent. f, entepicondyle
foramen; ipp, iliac posterior process. Lui (2015).
The second set of remains
comprise an occiput, a quadrate, a quadratojugal; a right caniniform process
with tusk, one centrum, five neural arches, four sacral vertebrae with ribs; a
right ilium, a left and right radius, a left and right tibiae and one claw,
also from the Baidaoyu exposure of the Tongchuan Formation. These remains are
assigned to the genus Parakannemeyeria
on the basis of the caniniform process and occiput, but due to the poor
preservation of the skull is not classified to species level.
Parakannemeyeria sp: (A) Right
caniniform process with tusk in lateral (A1) and medial (A2) views; (B) right
quadrate and quadratojugal in anterior (B1) and posterior (B2) views; (C)
occiput in anterior (C1) and posterior (C2) views; (D) neural arch of axis in
anterior (D1) and posterior (D2) views; (E) neural arch of a cervical in anterior
(E1) and posterior (E2) views; (F) four sacral vertebrae with ribs in dorsal
(F1) and ventral (F2) views; (G) ventral portion of right ilium in lateral (G1)
and medial (G2) views; (H) left radius in anterior (H1) and posterior (H2)
views; (I) left tibia in anterior (I1) and posterior (I2) views; (J) a claw in
dorsal (J1) and ventral (J2) views.
The third set of remains
comprises some vertebrae including an axis (the first vertebra, which connects
to the skull), a tibia and some bone fragments, from an exposure of the Tongchuan
Formation at Sanjiao in Liulin County. These remains are thought to belong to
either Sinokannemeyeria or Parakannemeyeria; the axis is very
similar to those of Sinokannemeyeria
and a dorsal vertebra resembles that of Sinokannemeyeria
yingchiaoensis, while the narrow centrum of the specimen resembles those of
Parakannemeyeria and the general
shape of the tibia resembles Parakannemeyeria
youngi and most of the other bones could belong to members of either genus.
Unidentified Kannemeyeriid: (A) Axis in anterior (A1), lateral (A2) and
posterior (A3) views; (B) a dorsal vertebra in lateral (B1) and posterior (B2)
views; (C) incomplete left precoracoid in medial view; (D) proximal portion of
left ulna in anterior (D1) and posterior (D2) views; (E) left tibia in anterior
view. Scale bars equal 2 cm. Abbreviations: cn.c, cnemial crest; n.s, neural
spine; od, odontoid; pap, parapophysis; przp, prezagapophysis; pzp, postzagapophysis;
s.n, sigmoid notch; tr.p, transverse process. Lui (2015).
The final set of remains
comprises an incomplete skull, an axial neural arch, a cervical, one incomplete
hand and some bone fragments from Sanjiao in Liulin County. This is poorly
preserved, and not assigned to any genus or species, however some observations
are made. The premaxila has a smooth surface lacking the lateral extension seen
in Sinokannemeyeria and Parakannemeyeria. The external naris is
small, there is no postnarial excavation and the caniform process extend
laterally, not ventrally, all character states seen in Rhadiodromus, Kannemeyeria
and Shaanbeikannemeyeria, but not Sinokannemeyeria or Parakannemeyeria. The size of the snout suggests the living animal
was considerably larger than Shaanbeikannemeyeria.
Based upon this the specimen is excluded from Sinokannemeyeria and Parakannemeyeria,
suggesting that at least three species are present in the total assemblage.
Unidentified Kannemeyeriid: (A) Incomplete skull in lateral (A1) and
ventral (A2) views; (B) one metacarpal and two manual phalanges (possible same
digit) in dorsal (B1) and ventral (B2) views; (C) a cervical in posterior (C1),
lateral (C2) and anterior (C3) views; (D) left half of axial neural arch in
anterior view; (E) an incomplete hand in dorsal view. Lui (2015).
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