Paleontological Research, vol. 9, no. 1, pp. 1–14, April 30, 2005 6 by the Palaeontological Society of Japan

Middle Permian ammonoids from the Kamiyasse-Imo district in the Southern Kitakami Massif, Northeast Japan

MASAYUKI EHIRO1 AND AKIHIRO MISAKI2

1The Tohoku University Museum, Sendai 980-8578, Japan (e-mail: [email protected]) 2Institute of Geology and Paleontology, Tohoku University, Sendai 980-8578, Japan (Present address: Division of Earth and Planetary Sciences, Graduate School of Science, Kyoto University)

Received April 23, 2004; Revised manuscript accepted January 11, 2005

Abstract. Middle Permian ammonoid faunas are recognized from the Hosoo and Kamiyasse Formations in the Kamiyasse-Imo district, north of Kesennuma, Southern Kitakami Massif, Northeast Japan. The fau- nas comprise the following genera: Parastacheoceras, Demarezites, Demarezites?, Waagenoceras, Timor- ites, Tauroceras?, Cardiella, Adrianites, Agathiceras, Agathiceras?, Paraceltites and Cibolites. Para- stacheoceras bidentatus gen. and sp. nov. is newly proposed. The genera Demarezites, Tauroceras, Cardiella and Adrianites are described for first time from Japan. Based on these ammonoids, the middle part of the Hosoo Formation, upper part of the Hosoo Formation to the lower middle part of the Kamiyasse Forma- tion, and upper middle part of the Kamiyasse Formation are correlatable with the Middle Permian Road- ian, Wordian and Capitanian, respectively. The discovery of genera Demarezites and Cardiella strongly supports the previous hypothesis that the South Kitakami Paleoland was located in the equatorial province during the Middle Permian.

Key words: Middle Permian ammonoid, Kamiyasse, Imo, Southern Kitakami, Equatorial Tethyan Province

Introduction been established, although the ammonoids indicated above are excellent index fossils. The Southern Kitakami Massif, Northeast Japan Recently we obtained some ammonoids from the occupies the southern half of the Kitakami Massif and Middle Permian strata in the district, with precise geotectonically belongs to the South Kitakami Belt. geographic and stratigraphic data, that include genera The belt was a part of the South Kitakami Paleoland important for biostratigraphy and paleobiogeography. (Ehiro, 1997), in which fossiliferous shallow marine The purpose of this paper is to describe these ammo- sediments were deposited during Middle Paleozoic to noids, to correlate the Middle Permian formations earliest Cretaceous time. The Kamiyasse-Imo district, in the Kamiyasse-Imo district with the global stan- north of Kesennuma City, Southern Kitakami Massif dard section, and to discuss their paleobiogeographic (Figure 1), has been well-known in Japan for its Per- significance. mian fossil localities and many paleontological studies have been carried out there (see Onuki, 1969; Tazawa, Regional geology and ammonoid faunas of the 1976). The previously known Middle Permian fauna Hosoo and Kamiyasse Formations includes some age-diagnostic genera, such as Waagen- oceras, Timorites, Paraceltites and Cibolites (Haya- The Kamiyasse-Imo district is situated in the border saka, 1940, 1963; Koizumi, 1975; Ehiro and Araki, area between Kesennuma City, Miyagi Prefecture and 1997). However, except for that described by the last Rikuzentakata City, Iwate Prefecture. The Kamiyasse authors, detailed stratigraphic and geographic infor- district belongs to Kesennuma City and Imo district is mation for this material is absent. For instance, local- in the southwestern part of Rikuzentakata City. The ities have merely been described as ‘‘Imo’’ or ‘‘Ka- Permian strata from the area have been divided in as- miyasse’’ with no stratigraphic data. Therefore, precise cending order into the Nakadaira, Ochiai and Nabe- ammonoid-based correlation for the Middle Permian koshiyama Formations (Ehiro, 1977). The middle part formations in the Kamiyasse-Imo district has not yet of the Ochiai Formation, dominated by calcareous 2 Masayuki Ehiro and Akihiro Misaki

this formation. We collected the following ammonoids from the middle and upper parts of this formation. Fossil localities and horizons are shown in Figures 2 and 3, respectively, and these ammonoid fossils are figured in Figures 4–7.

Loc. H-1 (Upper reaches of the Funaochizawa val- ley, a tributary of the Imosawa River in the Imo district): Demarezites?sp.andAgathiceras?sp., from loose mudstone blocks probably derived from the middle part of the Hosoo Formation. Loc. H-2 (Middle reaches of the Hachirozawa val- ley, a tributary of the Imosawa River): Adrianites sp., from mudstone of the middle part of the Ho- soo Formation. Loc. H-3 (Mouth of a small tributary of the Imo- sawa River): Demarezites sp. and Agathiceras sp., from mudstone of the middle part of the Ho- soo Formation. Loc. H-4 (Eastern ridge of the Ookadozawa valley, a tributary of the Hosoozawa River in the Ka- miyasse district): Cardiella sp., Waagenoceras sp. Agathiceras sp. and Paraceltites elegans Girty, Figure 1. Location map of the study area. from mudstone of the upper part of the Hosoo Formation. Loc. H-5 (Road-cut along the forest road in the southern basin of the Shigejizawa River in the sandstone and impure limestone, was separated into Kamiyasse district): Parastacheoceras bidentatus the Toyazawa Member. Recently, Misaki and Ehiro Ehiro and Misaki (gen. and sp. nov.), Tauroceras? (2004) reexamined the stratigraphy of the Ochiai For- sp. and Agathiceras sp., from laminated mudstone mation and divided it into the Hosoo, Kamiyasse and of the uppermost part of the Hosoo Formation. Kurosawa Formations from lower to upper (Figures 2 and 3). They roughly correspond to the lower, middle The Kamiyasse Formation ranges in thickness from (Toyazawa Member) and upper parts of the Ochiai 200 to 300 m and is dominated by calcareous sand- Formation, respectively. Permian strata having the stone, calcareous mudstone and impure limestone. same stratigraphy also occur in the Shishiori district, This formation yields many fusulinoideans, corals, Kesennuma City, to the east of Kamiyasse and to the brachiopods, molluscs and other fossils. Tazawa (1973, south of Imo. 1976) established two fusulinoidean zones in the Ka- The Nakadaira Formation distributed mainly in miyasse Formation: the lower Monodiexodina matsu- the Kamiyasse district consists predominantly of lime- baishi Zone and the upper Lepidolina multiseptata stone intercalated with conglomerate, sandstone and Zone. M. matsubaishi (Fujimoto), the index species of mudstone. The limestone yields the Early Permian the M. matsubaishi Zone, dominates in the lower and fusulinoideans Robustoschwagerina schellwieni Han- middle parts of this formation, but ranges upwards zawa and Pseudofusulina fusiformis (Schellwien and into the lower part of the L. multiseptata Zone (Ehiro Dyhrenfurth) (Tazawa, 1973, 1976), thus establishing and Misaki, 2004). The Wordian fusulinoidean genus a Sakmarian-Artinskian (Early Permian) age for the Cancellina has been reported from the lower part of formation. the M. matsubaishi Zone in the Setamai district of the The Hosoo Formation, 400 to 500 m thick, is pri- Southern Kitakami Massif (Choi, 1973). The L. multi- marily a mudstone unit with some lenticular sandstone septata Zone is characterized by L. multiseptata De- beds. One of the sandstone beds intercalated in the prat and Verbeekina verbeeki (Geinits). Genus Lep- upper horizon is rather thick in the northern part of idolina is widely accepted as an index fossil of the the Kamiyasse district, but thins laterally. No age- Capitanian. The Kamiyasse Formation yields the fol- diagnostic fossils had been reported previously from lowing ammonoids: Waagenoceras, Timorites, Para- Middle Permian ammonoids from Kitakami 3

Figure 2. Geologic map of the Kamiyasse-Imo district, Southern Kitakami Massif, Northeast Japan (simplified from Misaki and Ehiro, 2004), showing the ammonoid localities. Latitude and longitude values are referred to the Tokyo Datum. Plus 10.5 00 to the latitude and minus 12.7 00 to the longitude for the Japanese Geodetic Datum 2000. 4 Masayuki Ehiro and Akihiro Misaki

Figure 3. Generalized columnar section of the Permian formations in the Kamiyasse-Imo district (simplified from Misaki and Ehiro, 2004). Stratigraphic distributions of ammonoid fossils are also shown. Middle Permian ammonoids from Kitakami 5

Figure 4. Middle Permian ammonoids from the middle part of the Hosoo Formation. 1. Agathiceras sp., IGPS coll. cat. no. 109435, dorsal view, 1.3. 2. Agathiceras? sp., IGPS coll. cat. no. 109439, lateral view, 1.8. 3. Demarezites sp., IGPS coll. cat. no. 109430, ventral (a) and dorsal (b) views, 1.0. 4. Demarezites? sp., IGPS coll. cat. no. 109431, lateral view, 1.05. 5. Adrianites sp., IGPS coll. cat. no. 109434, lateral (a) and ventral (b) views, 1.8.

The Kamiyasse Formation yields the following ammonoids (Figures 8 and 9). Two specimens from locality Ky-3, housed in the Rikuzentakata City Mu- seum, are also listed here.

Loc. Ky-1 (Middle reaches of the Toyazawa River in the Shishiori district): Cibolites cf. uddeni Plummer and Scott, from mudstone intercalated in the sandstone beds of the middle part of the Kamiyasse Formation. Loc. Ky-2 (Upper reaches of the Nidanosawa Val- ley, a southern tributary of the Shigejizawa River): Cibolites cf. uddeni Plummer and Scott, from sandstone float, which contains many specimens of fusulinoidean species Monodiexodina matsu- baishi (Fujimoto). This ammonoid specimen pre- sumably came from the middle part of the Ka- miyasse Formation, because rocks belonging to Figure 5. External suture lines of Demarezites, Demare- the middle part of the formation are distributed zites?, Waagenoceras and Timorites. around the fossil locality and the lithofacies of the 1. Demarezites sp., IGPS coll. cat. no. 109430. 2. Demarezites? ammonoid and M. matsubaishi-bearing sandstone sp., IGPS coll. cat. no. 109431. 3. Waagenoceras sp., IGPS coll. is very similar to that in the lower to middle part cat. no. 109432. 4. Timorites sp., RCM F953. Scale bars are 1 cm: of the formation. bar A for figure 3, B for figures 1, 2 and 4. Loc. Ky-3 (Upper reaches of the Hachirozawa valley): Timorites sp. and Cibolites cf. uddeni celtites and Cibolites (Hayasaka, 1940, 1963; Koizumi, Plummer and Scott, from loose calcareous mud- 1975; Ehiro, 1998). These fusulinoidean and ammo- stone blocks, probably derived from the middle noid fossils enable correlation of this formation as a part of the Kamiyasse Formation. whole with a stratigraphic interval from the Roadian to Capitanian Stage (Middle Permian) (Ehiro, 1998), The Kurosawa Formation is composed mainly of although the precise stratigraphic levels of these am- mudstone and its total thickness exceeds 1000 m. monoids in this formation are not clear. Specimens of Lepidolina and ammonoids indicating 6 Masayuki Ehiro and Akihiro Misaki

Figure 6. Middle Permian ammonoids from the upper part of the Hosoo Formation. 1–2. Cardiella sp., 1. IGPS coll. cat. no. 109427, lateral (a) and ventral (b) views, 1.0, 2. Cardiella sp., IGPS coll. cat. no. 109428, lateral view, 1.7. 3–5. Agathiceras sp., 3. IGPS coll. cat. no. 109436, lateral view, 1.5, 4. IGPS coll. Cat. No. 109437, lateral (a) and ventral (b) views, 1.5, 5. IGPS coll. cat. no. 109438, lateral view, 1.7. 6. Waagenoceras sp., IGPS coll. cat. no. 109432, lateral (a) and ventral (b) views, 1.5. 7. Tauroceras? sp., IGPS coll. cat. no. 109433, lateral view, 1.0. 8–9. Paraceltites elegans Girty, 8. IGPS coll. cat. no. 109440, lateral view, 3.0, 9. IGPS coll. cat. no. 109441, 3.0. 10. Parastacheoceras bidentatus gen. and sp. nov., IGPS coll. cat. no. 109429 (Hol- otype), lateral (a) and ventral (b) views of the outer whorl, 1.5. and lateral (c) and ventral (d) views of the inner whorl, 1.3.

a Capitanian age have been discovered from the lower ezites has been known from the Middle Permian strata part (Ehiro and Araki, 1997; Loc. Ks-1). The ammo- of Timor and North American Southwest. It occurs noid fauna includes Jilingites kesennumensis Ehiro and more frequently in the Roadian, although there is a Araki, Stacheoceras sp., Timorites takaizumii Ehiro possibility that it ranges into the basal Wordian and Araki, Pseudagathiceras ornatum Ehiro and (Glenister and Furnish, 1987). Adrianites has been re- Araki, Propinacoceras sp. and Eumedlicottia primas ported from Artinskian to Kungurian strata of the (Waagen). Urals and Texas, and from the Roadian to Wordian (dominantly from the Wordian) in many parts of the Correlation of the Hosoo and Kamiyasse Formations Tethys region (Kullmann et al., 2000). Therefore, the with the standard stages based mainly on ammonoids middle part of the Hosoo Formation is assigned a Roadian age. Since the underlying Nakadaira Forma- The middle part of the Hosoo Formation yields tion yields Early Permian Sakmarian-Artinskian fusu- Demarezites and Adrianites (Figure 3). Both genera linoideans as previously stated, the lower part of the are described from Japan for the first time.Demar- Hosoo Formation is probably correlatable with the Middle Permian ammonoids from Kitakami 7

dentatus, Waagenoceras sp. Agathiceras sp., Taur- oceras?sp.andParaceltites elegans (Figure 3). The present discovery of Cardiella and Tauroceras from the Hosoo Formation is the first record from the Jap- anese Permian. Cardiella has been described from Upper Carboniferous to Kungurian strata, but domi- nantly in the Kungurian of the Pamirs (Leonova, 1981). Tauroceras ranges from the Roadian to Cap- itanian but dominantly in the Wordian (Kullmann et al., 2000). Parastacheoceras is a newly proposed genus closely related to Stacheoceras, that ranges from the Artinskian to Changhsingian (Kullmann et al., 2000) or from the Kungurian to Changhsingian (Leonova, 2002). Stacheoceras tietzei Gemmellaro, described from the Roadian? in Sicily by Gemmellaro (1887), Figure 7. Suture lines of Parastacheoceras and Cardiella. probably belongs to this new genus. The most im- 1a–c. Parastacheoceras bidentatus gen. and sp. nov., IGPS coll. portant genus for biostratigraphy in this horizon is cat. no. 109429 (holotype), external suture lines of the inner Waagenoceras. It is an index fossil of the Wordian whorl (a) and outer whorl (b), and internal suture line of the (Glenister et al., 1992; Jin et al., 1997), although it outer whorl (c). 2–3. External suture lines of Cardiella sp., 2. ranges up into the Capitanian. Agathiceras is a long- IGPS coll. cat. no. 109427, 3. IGPS coll. cat. no. 109428. Scale bar is 1 cm. ranging genus occurring in strata of Late Carbonifer- ous (Moscovian) to Wordian age (Kullmann et al., Kungurian, and the Kungurian-Roadian boundary lies 2000; Leonova, 2002). Genus Paraceltites ranges from somewhere in the lower-middle horizon of the Hosoo the Roadian to Capitanian, but P. elegans is restricted Formation. to the Roadian and Wordian formations (Spinosa The upper part of the Hosoo Formation contains et al., 1975). From these stratigraphic data, it is con- the ammonoids Cardiella sp., Parastacheoceras bi- cluded that the upper part of the Hosoo Formation

Figure 8. Middle Permian ammonoids from the middle part of the Kamiyasse Formation. 1. Timorites sp., RCM F953, lateral (a) and ventral (b) views, 1.05. 2–4. Cibolites cf. uddeni Plummer and Scott., 2a–b. IGPS coll. cat. no. 109443, lateral views, 0.9, 3. RCM F760, lateral view, 1.2, 4. IGPS coll. cat. no. 109442, lateral view, 1.2. 8 Masayuki Ehiro and Akihiro Misaki

the ammonoid faunas, that the South Kitakami Pa- leoland, to which the Southern Kitakami Massif be- longed, was located near the South China Continent in the Equatorial Tethyan Province during Middle to Late Permian time. The Middle and Upper Permian ammonoid faunas of the South Kitakami Massif con- tain genera characteristic of the Equatorial Tethyan Province, e.g., Timorites, Pseudogastrioceras, Para- celtites, Cibolites, Araxoceras, Eusanyangites and Ves- cotoceras. Recently, Dzhulfoceras,whichisalsoa characteristic Equatorial Tethyan ammonoid element, Figure 9. External suture lines of Cibolites cf. uddeni Plummer and Scott. was added in this Upper Permian fauna (Ehiro, 2001). 1. IGPS coll. cat. no. 109443. 2. RCM F953. Scale bar is 5 mm. Although some of the ammonoid genera newly reported here are cosmopolitan, Demarezites and Cardiella are restricted to the equatorial provinces (Equatorial Tethyan and Equatorial American). De- is Wordian in age, although the traditional range of marezites has only been known from Timor and the the genus Cardiella conflicts with this age assignment. American Southwest. Glenister and Furnish (1987) Consequently, the Roadian-Wordian boundary is considered that Wordian ammonoids Waagenoceras thought to be situated in the middle-upper part of the canadensis Nassichuk, described from the Cache Creek Hosoo Formation. Group in British Columbia, Western Canada (Nassi- Cibolites and Timorites have been known from the chuk, 1977), also belongs to the genus Demarezites, middle part of the Kamiyasse Formation (Figure 3), although Spinosa and Nassichuk (1994) treated it as a although their precise horizons are mostly unknown. species of genus Tongluceras. The distributional area Cibolites has been described from Wordian and Cap- of the Cache Creek Group is an accreted block and itanian strata, especially from the Capitanian of the considered to be derived from low latitudes more than Tethyan region and the American Southwest (Spinosa 1000 km to the south or southwest of the present po- et al., 1975). Timorites is an index fossil of the upper sition (Nassichuk, 1995). Permian species of Cardiella Middle Permian Capitanian Stage (Glenister et al., were widely distributed in the low latitudinal region 1992; Jin et al., 1997) and ranges up into the Upper in the Tethys (Leonova, 1981, 2002), except for C. Permian Wuchiapingian (Ehiro and Araki, 1997). ruzhencevi Leonova from the Artinskian of the Urals. Therefore, it is considered that a part (the upper The occurrence of these ammonoids in the South part?) of the middle part of the Kamiyasse Formation Kitakami Massif strongly supports the Ehiro’s (1997) is Capitanian in age and the Wordian-Capitanian opinion that the South Kitakami Paleoland was lo- boundary may be situated in the middle part of the cated in the Equatorial Tethyan Province during the Kamiyasse Formation (Ehiro, 1998), because the Middle to Late Permian. When Ehiro (1997) studied lower part of the Kamiyasse Formation, i.e., the lower the Permian ammonoid fauna of South Kitakami, part of the M. matsubaishi Zone, contains a Wordian no reliable Roadian ammonoids were known from fusulinoidean Cancellina as stated earlier. The upper there; this paper is the first one that describes the part of the Kamiyasse Formation and the lower part of Roadian ammonoids from the region. The Roadian the overlying Kurosawa Formation are also assigned ammonoid fauna comprises Demarezites, Agathiceras a Capitanian age, because they yield the Capitanian and Adrianites. Therefore, South Kitakami also ap- fusulinoidean Lepidolina multiseptata (Tazawa, 1973, pears to have been located in the Equatorial Tethyan 1976), and a Capitanian ammonoid fauna (Ehiro and Province during early Middle Permian Roadian time. Araki, 1997), respectively. Conclusions Paleobiogeography of the South Kitakami Paleoland during the Middle Permian The middle part of the Hosoo Formation yields the Roadian ammonoid Demarezites. On the other hand, Ehiro (1997) recognized four ammonoid provinces Wordian ammonoid elements, including Waageno- in the world during the Permian. They are: Boreal, ceras, Tauroceras?andParaceltites, were recovered Equatorial American, Equatorial Tethyan and Peri- from the upper part. Capitanian ammonoids such as Gondwanan Provinces. He stressed, on the basis of Timorites and Cibolites, probably derived from the Middle Permian ammonoids from Kitakami 9 middle part of the Kamiyasse Formation, are also de- on shell surface. Another specimen (109428) is a small scribed. Based on these ammonoids and previously fragment of a phragmocone. reported fusulinoidean and ammonoid data, the mid- Ventral lobe broad and divided by high, rounded dle part of the Hosoo Formation, upper part of the median saddle into two bidenticulated branches. At Hosoo Formation to lower–middle? part of the Ka- least four lobes on outer lateral side; first three are miyasse Formation and upper?-middle part of the tridenticulated and fourth may be bidenticulated. All Kamiyasse Formation to lower part of the Kurosawa saddles rounded. Formation are assigned Roadian, Wordian and Cap- itanian ages, respectively. Superfamily Cycloloboidea Zittel, 1895 The Roadian Demarezites and Wordian Cardiella, Family Vidrioceratidae Plummer and Scott, 1937 both newly discovered from the Hosoo Formation, Genus Parastacheoceras gen. nov. are indicative of the equatorial ammonoid provinces. Therefore, present ammonoid data strongly support Type species.—Parastacheoceras bidentatus sp. nov. the previous hypothesis that the South Kitakami re- by present designation. gion belonged to the Equatorial Tethyan Province Diagnosis.—Small-sized vidrioceratid with sub- during Middle Permian (Wordian) to Late Permian globular shell and closed umbilicus like Stacheoceras. time (Ehiro, 1997), and moreover they enable us to Suture also closely related to that of Stacheoceras, but refer this idea to strata of early Middle Permian all outer lateral lobes bifid. Roadian age. Discussion.—General conch shape and sutural pat- tern resemble Stacheoceras. All outer lateral lobes, Systematic description however, are bifid, differing from those of Stacheo- ceras species. Some of the outer lateral lobes of Sta- Specimens described in this paper are housed in the cheoceras are trifid. The outline of the inner suture is Institute of Geology and Paleontology, Tohoku Uni- quite similar to that of Stacheoceras. versity, Sendai City (IGPS) and in the Rikuzentakata The outer lateral lobes of Stacheoceras tietzei Gem- City Museum, Rikuzentakata City (RCM). mellaro, 1887 described from Sicily are also all bifid and therefore S. tietzei is considered to belong to this Subclass Ammonoidea Agassiz, 1847 new genus. Order Goniatitida Hyatt, 1884 Etymology.—The name refers to its resemblance to Suborder Goniatitina Hyatt, 1884 Stacheoceras Gemmellaro, 1887. Superfamily Marathonitoidea Ruzhentsev, 1938 Geologic age.—Middle Permian, Roadian? to Family Marathonitidae Ruzhentsev, 1938 Wordian. Genus Cardiella Pavlov, 1967 Parastacheoceras bidentatus sp. nov. Type species.—Cardiella gracia Pavlov, 1967 Figures 6.10a–d, 7.1a–c

Cardiella sp. Material.—Holotype, IGPS coll. cat. no. 109429 Figures 6.1–2, 7.2–3 collected by Y. Takaizumi from Loc. H-5. Cardiella sp. Misaki and Ehiro, 2004, p. 136, figs. 8.5a–c. Diagnosis.—Small-sized Parastacheoceras with subglobular shell and closed umbilicus. Shell surface Material.—Two specimens, IGPS coll. cat. no. probably smooth. Outer and inner lateral lobes all 109427 and 109428 from Loc. H-4. symmetrically bifid. Description.—Shell of one specimen (109427) in- Description.—A small natural cast of phragmocone volute and thickly lenticular in outline. Conch moder- obliquely deformed. Diameter of partly preserved ately large; diameter 49 mm in the deformed state. last whorl attains more than 30 mm. Shell involute Body chamber about one volution. At adoral end and subglobular in outline, having broadly convex height and width 29 and 18 mm, respectively. Um- sides and venter. Umbilical and ventral shoulders also bilicus almost closed, with steep umbilical wall. broadly rounded. Umbilicus very small and almost Lateral sides of conch broadly convex converging closed. Diameter, height and width of inner shell towards venter. Whorl cross section subtriangular about 23, 12 and 12 mm, respectively. Surface of cast with rounded umbilical and ventral shoulders. Venter smooth. broadly rounded, but acutely rounded on the adoral Suture rather well preserved. External suture con- part of the body whorl. Faint sigmoidal growth lines sists of a large and wide ventral lobe and many lateral 10 Masayuki Ehiro and Akihiro Misaki lobes. Ventral love divided by high median saddle into intensively serrated lateral lobes. Crests of saddles two wide bidenticulated branches. Five lateral lobes rounded. and two or three umbilical lobes in later stage. Former Based on the general shape of the suture this speci- lobes all symmetrically bifid and gradually diminish in men is considered to belong to either Demarezites size toward umbilicus. Latter ones pointed or rounded. or Waagenoceras. However, a more precise identifi- Inner suture composed of a deep trifid dorsal lobe and cation is not possible due to its very poor state of six bifid lateral lobes and some umbilical ones. preservation. Comparison.—Stacheoceras tietzei Gemmellaro (Gemmellaro, 1887, p. 28, pl. 5, figs. 1–3) has a lateral Genus Waagenoceras Gemmellaro, 1887 suture closely related with the present species and considered to belong to the genus Parastacheoceras.It Type species.—Waagenoceras mojsisovicsi Gem- differs from P. bidentus in having rather prominent mellaro, 1887 oblique transverse ribs and having asymmetrically bi- fid lateral lobes. Waagenoceras sp. Etymology.—The specific name is derived from its Figures 5.3, 6.6a–b shape of the bifid lateral lobes. Waagenoceras sp. Misaki and Ehiro, 2004, p. 136, figs. 8.2a–c.

Family Cyclolobidae Zittel, 1895 Material.—IGPS coll. cat. no. 109432 collected at Subfamily Cyclolobinae, Zittel, 1895 Loc. H-4. Genus Demarezites Ruzhentsev, 1955 Descriptive remarks.—A small phragmocone slightly deformed obliquely. Conch involute and sub- Type species.—Waagenoceras oyensi Gerth, 1950 globular in outline. Umbilicus small with steep umbil- ical wall. Lateral sides of conch broadly convex and Demarezites sp. whorl cross-section subelliptical with rounded umbili- Figures 4.3a–b, 5.1 cal and ventral shoulders. Shell diameter, height, Demarezites sp. Misaki and Ehiro, 2004, p. 136, figs. 8.1a–c. width and umbilical diameter at adoral end about 21, 11, 14 and 3 mm, respectively, in deformed state. Material.—IGPS coll. cat. no. 109430 collected from Suture characteristic of Family Cyclolobidae. Ven- Loc. H-3. tral lobe large and deep with rather simple median Descriptive remarks.—Half volution of phragmo- saddle. Six lateral lobes; about two-thirds of the sad- cone obliquely deformed. Conch, involute and ellipti- dles achieve denticulation. cal in outline, moderately large and attains diameter From the general shell shape, sutural trace and of about 40 mm in deformed state. Surface seems to the number of lateral lobes, the present specimen be smooth. clearly belongs to the genus Waagenoceras.However, Poorly preserved ammonitic outer suture slightly specific-level identification is difficult due to its small arched, consisting of a wide and deep ventral lobe and size and rather poor preservation. probably seven pairs of lobes on lateral sides. Ventral saddle rather simple in shape and about two-thirds Genus Timorites Haniel, 1915 height of ventral lobe. Lateral lobes strongly and complexly denticulated. Denticulation largely con- Type species.—Timorites curvicostatus Haniel, 1915 fined to lower two-thirds of lobes. Saddles rounded. Timorites sp. Demarezites?sp. Figures 5.4, 8.1a–b Figures 4.4, 5.2 Timorites sp. Ehiro, 1998, p. 151.

Material.—IGPS coll. cat. no. 109431 collected from Material.—RCM F953 collected from Loc. Ky-3. a float at Loc. H-1. Descriptive remarks.—An elliptically deformed, Descriptive remarks.—A fragment of body cham- moderately large phragmocone; diameter about ber. Conch strongly deformed and flattened, thus dif- 52 mm. Conch involute and subglobular in outline. At ficult to estimate original shape. An impression of last adoral end shell height, width and umbilical diameter septum, preserved. Suture rather poorly preserved, about 32, 15 and 12 mm, respectively. Broadly con- but characteristic of Family Cyclolobidae; at least five vex sides grade into acutely rounded venter. Umbili- Middle Permian ammonoids from Kitakami 11 cal wall almost perpendicular and umbilical shoulder Superfamily Agathiceratoidea Arthaber, 1911 acutely rounded. Family Agathiceratidae Arthaber, 1911 Suture lines not so wellpreserved, but characteristic Genus Agathiceras Gemmellaro, 1887 of Timorites as shown in Figure 5-4. Type species.—Agathiceras suessi Gemmellaro, Superfamily Popanoceratoidea Hyatt, 1900 1887 Family Popanoceratidae Hyatt, 1900 Agathiceras sp. Genus Tauroceras Toumanskaya, 1938 Figures 4.1, 6.3–5 Type species.—Popanoceras scrobiculatum Gem- Agathiceras sp. Misaki and Ehiro, 2004, p. 136, fig. 8.4 mellaro, 1887 Material.—Four specimens, IGPS coll. cat. no. Tauroceras?sp. 109435 collected from Loc. H-3, and IGPS coll. cat. no. 109436–109437 at Loc. H-4 and IGPS coll. cat. no. Figure 6.7 109438 at Loc. H-5 by Y. Takaizumi. Descriptive remarks.—Specimens small to moderate Material.—IGPS coll. cat. no. 109433 collected from size; diameter 23 to 30 mm in a deformed state. Conch Loc. H-5. involute and, due to the tectonic deformation, thinly Descriptive remarks.—A small fragmental speci- discoidal to spherical in outline, with an almost closed men, 2 2 cm in size, seems to be a part of flat lateral umbilicus. Sides flat or slightly convex and umbilical side. Growth lamellae sinuous and each lamella ven- shoulders rounded. Venter convex with rounded ven- trolaterally bifid. trolateral shoulders. Shell surface ornamented by The close resemblance of shell ornamentation to many fine spiral lirae. Suture not preserved. that of Tauroceras, especially T. scrobiculatum (Gem- mellaro), enables us to compare the present specimen Agathiceras?sp. with the genus Tauroceras. This identification is, how- ever, somewhat questionable, because of its very poor Figure 4.2 state of preservation. Material.—A fragmental specimen, IGPS coll. cat. no. 109439 collected from Loc. H-1. Superfamily Adrianitoidea Schindewolf, 1931 Descriptive remarks.—A small fragment about Family Adrianitidae Schindewolf, 1931 12 mm in size; seems to be a ventral part of whorl. Genus Adrianites Gemmellaro, 1887 Venter convex with rounded ventrolateral shoulders. Many fine spiral lirae on shell surface. Suture un- Type species.—Adrianites elegans Gemmellaro, known. Generic identification somewhat questionable, 1887 owing to poor state of preservation.

Adrianites sp. Order Ceratitida Hyatt, 1884 Figures 4.5a–b Superfamily Xenodiscoidea Frech, 1902 Family Paraceltitidae Spath, 1930 Material.—IGPS coll. cat. no. 109434 collected from Genus Paraceltites Gemmellaro, 1887 Loc. H-2. Descriptive remarks.—A small, obliquely deformed Type species.—Paraceltites elegans Girty, 1908 fragmental specimen consists of phragmocone and a part of body chamber. Conch subspherical in outline Paraceltites elegans Girty and somewhat depressed. Diameter attains about Figures 6.8–9 17 mm in deformed state. Body chamber surface with Paraceltites elegans Girty, 1908, p. 499, pl. 25, figs. 12–14; Plummer fine but distinct longitudinal lirae and transverse and Scott, 1937, p. 367, pl. 37, figs. 1–8; Miller and Furnish, growth lines forming a regular network; the former 1940, p. 67, pl. 22, figs. 1–10, text-fig. 17B; Yanagisawa, 1967, p. slightly prominent than the latter. 103, pl. 3, fig. 11; Spinosa et al., 1975, p. 249, pl. 1, pl. 2, figs. 1–7, pl. 3, figs. 1–9, text-figs. 3, 4, 5C, 10A, 11, 12; Zhao and Zheng, Poorly preserved suture on lateral side has some U- 1977, p. 248, pl. 5, figs. 11, 12; Liang and Guo, 1982, p. 278, pl. shaped lobes with somewhat pointed base and rounded 106, figs. 8, 9; Zheng, 1984, p. 191, pl. 1, figs. 1–7, text-figs. 8a, saddles. 8b; Misaki and Ehiro, 2004, p. 136, fig. 8-3. 12 Masayuki Ehiro and Akihiro Misaki

Paraceltites aff. elegans Girty. Bo¨ se, 1919, p. 110, pl. 5, figs. 33–38; 25, figs. 7, 8, text-fig. 18A; Miller in King et al., 1944, p. 124; Hayasaka, 1940, p. 424, text-figs. 2–4; Hayasaka, 1965, p. 17, pl. Miller, 1945, p. 345, pl. 50, fig. 9, text-figs. 3A, 3B. 3, fig. 2. Paraceltites multicostatus Bo¨ se, 1919, p. 108, pl. 5, figs. 19–32; Smith, Material.—Three specimens, IGPS coll. cat. no. 1932, p. 41, pl. 44, figs. 10, 12–14; Plummer and Scott, 1937, p. 368, pl. 37, figs. 9, 10; Miller and Furnish, 1940, p. 70, pl. 23, fig. 109442 collected by S. Hanamatsu from Loc. Ky-1, 9. RCM F760 from Loc. Ky-3, and IGPS coll. cat. no. Paralecanites altudensis Bo¨ se, 1919, p. 178, pl. 11, figs. 28–45; 109443 collected by Y. Suzuki from Loc. Ky-2. PlummerandScott,1937,p.372,pl.37,figs.11–13. Descriptive remarks.—Specimens moderate to large Paraceltites bamianus Reed, 1931, p. 39, pl. 4, figs. 16, 16a. in size, with conch diameter 40 to 65 mm in elliptically Paraceltites ornatus Miller and Furnish, 1940, p. 68, pl. 6, fig. 5, pl. 23, figs. 4, 5, 8, text-figs. 17A, 17C; Miller in King et al., 1944, p. deformed state. Ratios of umbilical diameter to shell 121, pl. 24, figs. 4–6, text-fig. 29A. diameter of evolute shells about 0.38 (IGPS coll. cat. Paraceltites sellardsi Miller and Furnish, 1940, p. 69, pl. 23, figs. 6, 7. no. 109442) and 0.40 (IGPS coll. cat. no. 109443). Paraceltites altudensis (Bo¨ se). Miller and Furnish, 1940, p. 70, pl. 23, Conch thinly lenticular with gently convex sides and figs. 1–3, pl. 24, fig. 7, text-fig. 17E; Miller in King et al., 1944, p. acute venter. Fine radial ribs on flanks of inner vol- 123, pl. 41, figs. 1–6, text-fig. 29B; Zhao and Zheng, 1977, p. 248, pl. 5, figs. 15, 16. utions, but indistinct at maturity. IGPS coll. cat. no. Paracibolites costatus Hayasaka, 1947, p. 32, pl. 2, figs. 6, 7, text-fig. 109443 has longitudinal lirae on ventral sides. Suture 5. only partly preserved in RCM F760 and IGPS coll. Paraceltites xizangensis Liang, 1976, p. 219, pl. 1, figs. 5–8. cat. no. 109443. Two rounded lobes on lateral side and Paraceltites cf.elegansGirty. Xu in Xu and Wei, 1977, p. 574, pl. 216, third one probably on umbilical shoulder to umbilical figs. 11, 12. Paraceltites cf. multicostatus (Bo¨ se). Xu in Xu and Wei, 1977, p. 574, wall. pl. 216, figs. 9–10. Based on the shell outline and lenticular conch sec- Paraceltites hunanensis Xu in Xu and Wei, 1977, p. 575 pl. 216, figs. tion, the present specimens are comparable with Ci- 4–5. bolites uddeni Plummer and Scott. However, whether or not the present species is conspecific with the latter Material.—Two specimens, IGPS coll. cat. no. is somewhat questionable, because the conch of the 109440 and 109441 collected from Loc. H-4. former is rather poorly preserved and the suture is Descriptive remarks.—Specimens small; conch di- only imperfectly known. ameter 11.5 (IGPS coll. cat. no. 109440) and 11.7 mm (109441). Conch evolute; ratios of umbilical diameter Acknowledgements to shell diameter 0.48 and 0.52. Conch thinly to thickly discoidal with parallel sides, rounded ventrolateral We are grateful to C. Spinosa for critical reading of shoulders and narrowly rounded venter. Shell surface the manuscript and helpful comments. Y. Suzuki, Y. ornamented by fine sinuous growth lines and ribs. Takaizumi and S. Hanamatsu are cordially thanked Ribs absent or faintly recognizable on venter. Suture for donation of ammonoid specimens. We also thank not preserved. T. Leonova for providing literatures and the Riku- Spinosa et al. (1975) reexamined the specific classi- zentakata City Museum for permission to study speci- fication of the genus Paraceltites. 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Contributions from the Institute of Geology Figures 8.2–4, 9.1–2 and Paleontology, Tohoku University, no. 77, p. 1–37. (in Cibolites sp. Ehiro, 1998, p. 151. Japanese with English abstract) Compare.— Ehiro, M., 1997: Ammonoid palaeobiogeography of the South Cibolites uddeni Plummer and Scott, 1937, p. 373, pl. 37, figs. 14, 15, Kitakami Palaeoland and palaeogeography of eastern text-fig. 79; Miller and Furnish, 1940, p. 72, pl. 6, figs. 1–4, pl. Asia during Permian to Triassic time. In Jin Yu-Gan and Middle Permian ammonoids from Kitakami 13

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