Xitun Formation
Geological formation in Yunnan, China
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The Xitun Formation is a palaeontological formation which is named after Xitun village in Qujing, a location in South China. This formation includes many remains of fossilized fish and plants of the Early Devonian period (Late Lochkovian).[1][2] It was originally referred to as the Xitun Member of the Cuifengshan Formation (now the Cuifengshan Group).[3]
| Xitun Formation | |
|---|---|
| Stratigraphic range: | |
| Type | Geological formation |
| Unit of | Cuifengshan Group[1] |
| Underlies | Guijiatun Formation[2] |
| Overlies | Xiaxishancun Formation[2] |
| Lithology | |
| Primary | Calciferous mudstones[2] |
| Location | |
| Coordinates | 25°29.853'N and 103°46.309'E[2] |
| Region | Yunnan Province |
| Country | China |
| Extent | Qujing |
| Type section | |
| Named for | Xitun village |
Fossil content
Color key
|
Notes Uncertain or tentative taxa are in small text; |
Animals
Acanthodians
| Acanthodians reported from the Xitun Formation | |||||
|---|---|---|---|---|---|
| Genus | Species | Presence | Material | Notes | Images |
| Ischnacanthidae | Genus indet. | Qujing.[3] | 4 isolated scales (V7218.1, 3, 6 & 8) & 2 longitudinal sections (V7218.4 & 7).[3] | Similar to Ischnacanthus & Acanthodes, may be referrable to Youngacanthus. | |
| Nostolepis | N. amplifica | Xitun, Xishan subdistrict, Qujing.[4] | 43 trunk scales.[4] | ||
| N. consueta | Xitun, Xishan subdistrict, Qujing.[4] | Around 25 trunk scales.[4] | |||
| N. digitus | Xitun, Xishan subdistrict, Qujing.[4] | 28 trunk scales.[4] | |||
| N. qujingensis | Xitun, Xishan subdistrict, Qujing.[4] | 19 trunk scales.[4] | |||
| N. striata | Xitun, Xishan subdistrict, Qujing.[4] | 69 trunk scales.[4] | |||
| N. sp. indet. | Qujing.[3] | Body scales.[3] | |||
| Youngacanthus | Y. gracilis | Qujing.[3] | Jaw elements & teeth.[3] | An ischnacanthid. | |
Actinopterygians
| Actinopterygians reported from the Xitun Formation | |||||
|---|---|---|---|---|---|
| Genus | Species | Presence | Material | Notes | Images |
| Meemannia | M. eos | Xitun village, Qujing.[5] | An early ray-finned fish, formerly thought to be a lobe finned fish.[6] | ||
Arthropods
| Arthropods reported from the Xitun Formation | |||||
|---|---|---|---|---|---|
| Genus | Species | Presence | Material | Notes | Images |
| Qujingopterus[7] | Q. spineus | A stylonurid eurypterid |  | ||
Chondrichthyes
| Chondrichthyes reported from the Xitun Formation | |||||
|---|---|---|---|---|---|
| Genus | Species | Presence | Material | Notes | Images |
| Changolepis | C. tricuspidus | Qujing.[3] | 10 scales of various growth stages.[3] | ||
| Chondrichthyes | Genus indet. | Qujing.[3] | 4 isolated teeth (V7221.1, 2, 3 & 4). | May belong to Gualepis or Changolepis. | |
| Gualepis | G. elegans | Xitun, Qilin district, Qujing.[8] | Thousands of isolated scales.[3][8] | ||
| Ohiolepis? | O.? xitunensis | Qujing.[3] | A complete scale (V7233.1) & an incomplete scale (V7223.2).[3] | ||
| Peilepis | P. solida | Qujing.[3] | A body scale (V7222).[3] | ||
Jawless fish
| Jawless fish reported from the Xitun Formation | |||||
|---|---|---|---|---|---|
| Genus | Species | Presence | Material | Notes | Images |
| Parathelodus | P. asiaticus | Qilin district, Qujing.[9] | Body scales.[9] | A thelodont also known from the Xishancun Formation. | |
| P. cornuformis | Qilin district, Qujing.[9] | Body scales.[9] | A thelodont also known from the Xishancun Formation. | ||
| P. liaokuoensis | Qilin district, Qujing.[9] | Body scales.[9] | A thelodont also known from the Xishancun Formation. | ||
| P. scitulus | Qilin district, Qujing.[9] | A complete body scale (IVPP V 12156.1).[9] | A thelodont also known from the Xishancun Formation. | ||
| P. trilobatus | Qilin district, Qujing.[9] | Body scales.[9] | A thelodont also found in the Xishancun Formation. | ||
| P. wangi | Qilin district, Qujing.[9] | Body scales.[9] | A thelodont also known from the Xishancun Formation. | ||
| P. xitunensis | Qilin district, Qujing.[9] | A complete body scale (IVPP V 26113.1).[9] | A thelodont. | ||
| Turinia | T. asiatica | Qujing.[3] | Multiple scales.[3] | A thelodont. |  |
| Xitunaspis | X. magnus | Qujing.[10] | 4 headshields.[10] | A galeaspid. | |
Placoderms
| Placoderms reported from the Xitun Formation | |||||
|---|---|---|---|---|---|
| Genus | Species | Presence | Material | Notes | Images |
| Antiarchi | Unnamed antiarch | Qujing.[1] | MNHN-CHD02 & V10515.[1] | Originally referred to ?Xichonelepis. | |
| Asterosteidae | Gen. et. sp. indet. | Qujing.[11] | Part of the head shield.[11] | Very similar to Gemuendina.[11] | |
| Chuchinolepis | C. gracilis | Qujing.[1] | Detached plates.[1] | A chuchinolepidid also known from the Xishancun Formation. | |
| C. qujingensis | Plates.[1] | A chuchinolepidid also known from the Xishancun Formation. | |||
| C. robusta | Qujing.[1] | A detached AVL plate (V10512).[1] | A chuchinolepidid. | ||
| C. sulcata | Qujing.[1] | Trunkshield, plates & incomplete pectoral fin.[1] | A chuchinolepidid. | ||
| Gavinaspis | G. convergens | Qujing.[12] | Skull remains.[12] | A phyllolepid. | |
| Parayunnanolepis | P. xitunensis | Almost-complete specimen.[13] | A yunnanolepidid. |  | |
| Phymolepis | P. cuifengshanensis | Cuifengshan and Liaokuoshan, Qujing.[1][14] | Plates.[1][14] | A yunnanolepidid also known from the Xishancun Formation. |  |
| P. guoruii | Qujing.[1] | Trunk-shields & plates.[1] | A yunnanolepidid. | ||
| Szeaspis | S. yunnanensis | Qujing.[15] | Neurocranium & associated skull roof (IVPP V 5810a-b).[15] | Preoccupied genus name, renamed Szelepis. | |
| Szelepis | S. yunnanensis | Qujing.[15] | Neurocranium & associated skull roof (IVPP V 5810a-b).[15] | An actinolepid originally named Szeaspis. | |
| Yunnanolepis | Y. porifera | Qujing.[1] | A yunnanolepidid also known from the Xishancun Formation. | ||
| Y. sp. | Qujing.[1] | A trunk-shield associated with part of skull roof (V10514).[1] | A yunnanolepidid, specimen formerly assigned to Vanchienolepis. | ||
| Zhanjilepis | Z. aspratilis | Qujing.[1] | Plates.[1] | A yunnanolepidid also known from the Xishancun Formation. |  |
Sarcopterygians
| Sarcopterygians reported from the Xitun Formation | |||||
|---|---|---|---|---|---|
| Genus | Species | Presence | Material | Notes | Images |
| Achoania | A. jarvikii | Qujing.[16] | Anterior cranial portion.[16] | A basal lobe finned fish. | |
| Diabolepis | D. speratus | Xichong, Qujing.[17] | Multiple specimens.[17][18] | A dipteriform originally named Diabolichthys. | |
| Psarolepis | P. romeri | Xichong, Qujing.[19] | 4 anterior cranial portions, a posterior cranial portion, 2 complete lower jaws & an incomplete lower jaw.[19] | A basal lobe finned fish. |  |
| Styloichthys | S. changae | Qujing.[20] | Multiple specimens.[20] | A basal coelacanth.[21] |  |
| Youngolepis | Y. praecursor | Numerous specimens.[22] | A basal lobe finned fish also known from the Bac Bun Formation. |  | |
Plants
| Plants reported from the Xitun Formation | |||||
|---|---|---|---|---|---|
| Genus | Species | Presence | Material | Notes | Images |
| Gen. nov. A | Huaguo Hill, Shengfeng district of Qujing city.[2] | Numerous specimens.[2] | |||
| aff. Huia | aff. H. sp. | Huaguo Hill, Shengfeng district of Qujing city.[2] | PKU-XH214.[2] | A lycophyte. | |
| Unnamed spike | Huaguo Hill, Shengfeng district of Qujing city.[2] | A poorly preserved terminal spike (PKU-XH215a, 215b).[2] | Probably from a zosterophyll. | ||
| Xitunia | X. spinitheca | Qujing.[23] | A zosterophyll. | ||
| Zosterophyllum | Z. minorstachyum | Qujing.[23] | A zosterophyll. |  | |
| Z. shengfengense | A building site at Huaguo Hill, Shengfeng District, Qujing City.[24] | A nearly entire individual plant preserved as a compression (PUH-QXI01-1), and its counterpart (PUH-QXI01-1').[24] | A zosterophyll. | ||
See also
- List of fossil sites— (with link directory)
