# Xitun Formation

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). It was originally referred to as the Xitun Member of the Cuifengshan Formation (now the Cuifengshan Group).

## Fossil content

| Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon | Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited. |

### Vertebrates
#### Acanthodians

Acanthodians reported from the Xitun Formation :
| Genus | Species | Presence | Material | Notes |
| Ischnacanthidae | Genus indet. | Qujing. | 4 isolated scales (V7218.1, 3, 6 & 8) & 2 longitudinal sections (V7218.4 & 7). | Similar to Ischnacanthus & Acanthodes, may be referrable to Youngacanthus. |
| Nostolepis | N. amplifica | Xitun, Xishan subdistrict, Qujing. | 43 trunk scales. | |
| Nostolepis | N. consueta | Xitun, Xishan subdistrict, Qujing. | Around 25 trunk scales. | |
| Nostolepis | N. digitus | Xitun, Xishan subdistrict, Qujing. | 28 trunk scales. | |
| Nostolepis | N. qujingensis | Xitun, Xishan subdistrict, Qujing. | 19 trunk scales. | |
| Nostolepis | N. striata | Xitun, Xishan subdistrict, Qujing. | 69 trunk scales. | |
| Nostolepis | N. sp. indet. | Qujing. | Body scales. | |
| Youngacanthus | Y. gracilis | Qujing. | Jaw elements & teeth. | An ischnacanthid. |

#### Actinopterygians

Actinopterygians reported from the Xitun Formation :
| Genus | Species | Presence | Material | Notes | Images |
| Meemannia | M. eos | Xitun village, Qujing. | | An early ray-finned fish, formerly thought to be a lobe finned fish. | |

#### Arthropods

Arthropods reported from the Xitun Formation :
| Genus | Species | Presence | Material | Notes | Images |
| Qujingopterus | Q. spineus | | | A stylonurid eurypterid | |

#### Chondrichthyes

Chondrichthyes reported from the Xitun Formation :
| Genus | Species | Presence | Material | Notes |
| Changolepis | C. tricuspidus | Qujing. | 10 scales of various growth stages. | |
| Chondrichthyes | Genus indet. | Qujing. | 4 isolated teeth (V7221.1, 2, 3 & 4). | May belong to Gualepis or Changolepis. |
| Gualepis | G. elegans | Xitun, Qilin district, Qujing. | Thousands of isolated scales. | |
| Ohiolepis? | O.? xitunensis | Qujing. | A complete scale (V7233.1) & an incomplete scale (V7223.2). | |
| Peilepis | P. solida | Qujing. | A body scale (V7222). | |

#### Jawless fish

Jawless fish reported from the Xitun Formation :
| Genus | Species | Presence | Material | Notes |
| Parathelodus | P. asiaticus | Qilin district, Qujing. | Body scales. | A thelodont also known from the Xishancun Formation. |
| Parathelodus | P. cornuformis | Qilin district, Qujing. | Body scales. | A thelodont also known from the Xishancun Formation. |
| Parathelodus | P. liaokuoensis | Qilin district, Qujing. | Body scales. | A thelodont also known from the Xishancun Formation. |
| Parathelodus | P. scitulus | Qilin district, Qujing. | A complete body scale (IVPP V 12156.1). | A thelodont also known from the Xishancun Formation. |
| Parathelodus | P. trilobatus | Qilin district, Qujing. | Body scales. | A thelodont also found in the Xishancun Formation. |
| Parathelodus | P. wangi | Qilin district, Qujing. | Body scales. | A thelodont also known from the Xishancun Formation. |
| Parathelodus | P. xitunensis | Qilin district, Qujing. | A complete body scale (IVPP V 26113.1). | A thelodont. |
| Turinia | T. asiatica | Qujing. | Multiple scales. | A thelodont. |
| Xitunaspis | X. magnus | Qujing. | 4 headshields. | A galeaspid. |

#### Placoderms

Placoderms reported from the Xitun Formation :
| Genus | Species | Presence | Material | Notes |
| Antiarchi | Unnamed antiarch | Qujing. | MNHN-CHD02 & V10515. | Originally referred to ?Xichonelepis. |
| Asterosteidae | Gen. et. sp. indet. | Qujing. | Part of the head shield. | Very similar to Gemuendina. |
| Chuchinolepis | C. gracilis | Qujing. | Detached plates. | A chuchinolepidid also known from the Xishancun Formation. |
| Chuchinolepis | C. qujingensis | | Plates. | A chuchinolepidid also known from the Xishancun Formation. |
| Chuchinolepis | C. robusta | Qujing. | A detached AVL plate (V10512). | A chuchinolepidid. |
| Chuchinolepis | C. sulcata | Qujing. | Trunkshield, plates & incomplete pectoral fin. | A chuchinolepidid. |
| Gavinaspis | G. convergens | Qujing. | Skull remains. | A phyllolepid. |
| Parayunnanolepis | P. xitunensis | | Almost-complete specimen. | A yunnanolepidid. |
| Phymolepis | P. cuifengshanensis | Cuifengshan and Liaokuoshan, Qujing. | Plates. | A yunnanolepidid also known from the Xishancun Formation. |
| Phymolepis | P. guoruii | Qujing. | Trunk-shields & plates. | A yunnanolepidid. |
| Szeaspis | S. yunnanensis | Qujing. | Neurocranium & associated skull roof (IVPP V 5810a-b). | Preoccupied genus name, renamed Szelepis. |
| Szelepis | S. yunnanensis | Qujing. | Neurocranium & associated skull roof (IVPP V 5810a-b). | An actinolepid originally named Szeaspis. |
| Yunnanolepis | Y. porifera | Qujing. | | A yunnanolepidid also known from the Xishancun Formation. |
| Yunnanolepis | Y. sp. | Qujing. | A trunk-shield associated with part of skull roof (V10514). | A yunnanolepidid, specimen formerly assigned to Vanchienolepis. |
| Zhanjilepis | Z. aspratilis | Qujing. | Plates. | A yunnanolepidid also known from the Xishancun Formation. |

#### Sarcopterygians

Sarcopterygians reported from the Xitun Formation :
| Genus | Species | Presence | Material | Notes |
| Achoania | A. jarvikii | Qujing. | Anterior cranial portion. | A basal lobe finned fish. |
| Diabolepis | D. speratus | Xichong, Qujing. | Multiple specimens. | A dipteriform originally named Diabolichthys. |
| Psarolepis | P. romeri | Xichong, Qujing. | 4 anterior cranial portions, a posterior cranial portion, 2 complete lower jaws & an incomplete lower jaw. | A basal lobe finned fish. |
| Styloichthys | S. changae | Qujing. | Multiple specimens. | A basal coelacanth. |
| Youngolepis | Y. praecursor | | Numerous specimens. | A basal lobe finned fish also known from the Bac Bun Formation. |

### Plants

Plants reported from the Xitun Formation :
| Genus | Species | Presence | Material | Notes |
| Gen. nov. A | | Huaguo Hill, Shengfeng district of Qujing city. | Numerous specimens. | |
| aff. Huia | aff. H. sp. | Huaguo Hill, Shengfeng district of Qujing city. | PKU-XH214. | A lycophyte. |
| Unnamed spike | | Huaguo Hill, Shengfeng district of Qujing city. | A poorly preserved terminal spike (PKU-XH215a, 215b). | Probably from a zosterophyll. |
| Xitunia | X. spinitheca | Qujing. | | A zosterophyll. |
| Zosterophyllum | Z. minorstachyum | Qujing. | | A zosterophyll. |
| Zosterophyllum | Z. shengfengense | A building site at Huaguo Hill, Shengfeng District, Qujing City. | A nearly entire individual plant preserved as a compression (PUH-QXI01-1), and its counterpart (PUH-QXI01-1’). | A zosterophyll. |