The enigmatic temnospondyl amphibian Tungussogyrinus bergi Efremov, 1939 shares
clear synapomorphies with other branchiosaurids indicated by an anteriorly elongated infratemporal
fossa and small branchial denticles. Therefore Tungussogyrinus clearly belongs
to the dissorophoid family Branchiosauridae. This species is characterized by a
number of derived features among temnospondyls: (1) an unusually elongated anterodorsal
process of the ilium; (2) the character complex concerning the tricuspid dentition.
Tungussogyrinus differs from all other branchiosaurids in these two autapomorphic characters.
Herein, Tungussogyrinus is thought to represent the closest relative of a clade including
all other branchiosaurids with its placement outside of this clade associated with
a new feeding strategy to scrape algae with the tricuspid anterior dentition and the gracile
built snout region. The subfamily Tungussogyrininae Kuhn, 1962 is newly defined here
by the two derived characters of Tungussogyrinus bergi. All other branchiosaurid genera
and species are included in a second subfamily Branchiosaurinae Fritsch, 1879.

Order Temnospondyli Zittel, 1888
Superfamily Dissorophoidea Bolt, 1969
Family Branchiosauridae Fritsch, 1879
Subfamily Tungussogyrininae Kuhn, 1962
Tungussogyrinus Efremov, 1939
Type species. Tungussogyrinus bergi Efremov, 1939
Tungussogyrinus bergi Efremov, 1939
Figures 1–6, 9A–B, 10A–C, 11A–B, 12A–B, 13A–B
Holotype. Specimen PIN 206/1a, b; PIN 206/1a was figured by Efremov
(1939), Bystrow (1939), and reproduced in Shishkin (1998), but
it is missing now. The counterpart PIN 206/1b was first figured in
Shishkin (1998) and is shown here in Figure 2.
Type locality. Between the mouths of Upper and Lower Lyulyukta
Creeks along the Lower Tunguska River, Central Siberia.
Type horizon. Dvuroginsk Horizon of the volcanogenic Tunguska strata,
lower part of the Bugarikta Formation, Konvunchanian Group,
Late Permian to Early Triassic (Shishkin 1998).
Additional material. The same horizon as stratum typicum, 1 km
downstream of the mouth of the Upper Lyulyukta River (PIN 4262/
1a, b; Fig. 3) and the Anakit River (all other specimens from
PIN 4262/. . .; Figs 4–6).
The counterpart of the holotype PIN 206/1b and additional material
collected in 1966 and a PIN-expedition headed by S. N. Getmanov
in 1986, both under the number PIN 4262/. . .. Fourteen specimens are
figured here (Figs 2–6), eight of which are figured for the first time
(Figs 4, 5A–E, 6C–D, G–H).
Diagnosis. Characters comparable to lissamphibians, but derived relative
to other branchiosaurids: (1) an unusually elongated anterodorsal
process of the ilium as autapomorphic feature; (2) tricuspid teeth,
homoplastic in respect to the microsaur Batropetes, but an autapomorphy
with respect to branchiosaurids: in Tungussogyrinus bergi the tricuspid
teeth are labiolingually compressed with mesiodistally aligned
and slightly lingually curved cuspules; teeth with wide bases and a
decreasing number of the teeth to six in the premaxilla; the tooth
bearing portion of the premaxilla is low and the nasal and median
intranasal fenestra in the snout region are large.
Character of uncertain polarity, but unique within temnospondyls:
the second and third fingers of the manus are of equal length.
Synapomorphies shared by all branchiosaurids including Tungussogyrinus
bergi: (1) the anterior expansion of the infratemporal fossae
on the palate up to the anterior y-shaped palatine resulting in a gap
between ectopterygoid and maxilla; (2) the branchial denticles have a
small rounded base and one (? or possibly more) tooth like processes.
Characters shared with only some other branchiosaurids: Elongated
preorbital region with long nasal and vomer as known from Melanerpeton
Fritsch, 1878; expanded intraorbital region as comparable with
Apateon v. Meyer, 1844; foreshortened postorbital region with short
postorbital and supratemporal as known from Melanerpeton gracile
(Credner, 1881) (as Apateon gracilis in Schoch & Frbisch 2006) and
Branchiosaurus salamandroides; frontals very short, do not extend beyond
the anterior margin of the orbit; orbit elongated as known from
Melanerpeton; pre- and postfrontal in contact as known from Apateon
dracyiensis (Boy, 1972) and Branchiosaurus salamandroides; very
short maxilla and a gap between maxilla and jugal as partly known
from Apateon, Melanerpeton and Schoenfelderpeton Boy, 1986; jugal
with short anterior process in contrast to Branchiosaurus salamandroides;
robust shape of parasphenoid as known from Melanerpeton
gracile, Apateon dracyiensis and Branchiosaurus salamandroides;
palatine and ectopterygoid short as known from Apateon; elongated
humerus as known from Apateon dracyiensis; second metacarpal and
the proximal phalanx are more elongated as in the third digit as
known from Apateon dracyiensis and A. kontheri Werneburg, 1988a;
large transverse process completely on the neural arch as known from
Apateon dracyiensis.