Ichnofossils
Genus

Chondrites Sternberg, 1833

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Taxon description

Baucon et al., 2020c

Emended diagnosis: regularly branching tunnel system consisting of a small number of sub-vertical master-shafts, connected to the ancient sediment-water interface, that branches at depth to form a dendritic network. Fill can be active or passive (diagnosis emended after Osgood, 1970; Fürsich, 1974; Fu, 1991; Uchman, 1995; Blissett and Pickerill, 2004; Uchman et al., 2012).

Remarks: Non-radial forms (hypidiomorphic) may be included within the ichnogenus.The tunnels of Chondrites neither touch nor cross each other (Fu, 1991), although some exceptions are reported (Blissett and Pickerill, 2004; Uchman et al., 2012). Branching may occur in a single plane or as three-dimensional forms, and may consist of up to six orders of branching (Fu, 1991). According to Fu (1991), the branching angle may range from 15° to 90° with an average value between 30°- 60°. The burrow fill is typically uniform/structure-less, though there are some rare accounts of meniscate fill (Fu, 1991). Burrow diameter is narrow and varies between burrow systems (1−5 mm according to Fu (1991); 0.1–10 mm according to Savrda and Bottjer, 1991), but it is generally constant within a single system (Fu, 1991; Savrda and Bottjer, 1991). According to Uchman (1999), tunnels are narrower than 0.95 mm.

Fernández & Pazos, 2012

Remarks. Chondrites is ethologically classified as a feeding trace (fodinichnia). It is generally assigned to depositivorous and/or suspensivorous annelids or sipunculids.

Knaust, 2017

Morphology, Fill and Size: Chondrites is one of the most common and widely distributed trace fossils; due to its rootlike appearance it was originally interpreted as a plant fossil.  It consists of tunnel systems possessing a single or a small number of master shafts, presumably open to the surface, which ramifies with depth under acute angle to form a dendritic or root-like system (Osgood 1970; Fu 1991). Most of the burrows show an active fill, sometimes with portions preserving a meniscate structure. The burrows are unlined. The tunnel diameter remains constant in different parts of the burrow and typically is in the range of less than 1 mm to a few millimeters.

Howard & Frey, 1984

Diagnosis: Dendritic, smooth walled, regularly but asymmetrically branched small burrow systems that ordinarily do not interpenetrate or interconnect. Diameter of components within a given system remains more or less constant.

Mángano et al., 2002a

Recent work suggests that Chondrites may represent specialized feeding behavior that involves chemosymbiosis, being interpreted as a sulfide pump (Fu, 1990, Seilacher, 1990; Bromley, 1996). It has been regarded that the Chondrites animal developed adaptations to cope with oxygen-depleted conditions (Bromley & Ekdale, 1984; Savdra, 1992).

Selection of related publications
Hanken, N.-M., Uchman, A., Nielsen, J. K., Olaussen, S., Eggebø, T., Steinsland, R. 2016. Late Ordovician trace fossils from offshore to shallow water mixed siliciclastic and carbonate facies in the Ringerike Area, Oslo Region, Norway.Ichnos 23 , 3-4,189-221. DOI:10.1080/10420940.2016.1199427
Mikuláš R., Dronov, A. V. 2005. Trace fossils.6th Baltic Stratigraphical Conference, IGCP 503 Meeting, August 23-25, 2005. Cambrian and Ordovician of St. Petersburg region. Guidebook of the pre-conference field trip , pp. 33-38.
Elias, R. J., Nowlan, G. S., Bolton, T. E. 1988. Paleontology of the type section, Fort Garry Member, Red River Formation (Upper Ordovician), southern Manitoba.
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Classification
Organism groupBiota
Ichnofossil groupIchnofossils
Soft-sediment trace fossils
Trackways and scratch imprints
OrderBiformitidae
FamilyArenicolitidae
Arthrophycidae
Asteriacitidae
Rhizocoralliidae
Rosselichnidae
Siphonichnidae
GenusAcanthorhaphe
Aglaspidichnus
Agrichnium
Altichnus
Amanitichnus
Amphorichnus
Ancorichnus
Angulichnus
Arachnomorphichnus
Arachnostega
Arborichnus
Archaeonassa
Arcuatichnus
Arenituba
Artharia
Asaphoidichnus
Asterichnus
Asterosoma
Astropolichnus
Aulichnites
Avipeda
Avolatichnium
Balanoglossites
Baroccoichnites
Beaconites
Bergaueria
Bestiopeda
Bicavichnites
Bichordites
Bifasciculus
Bifungites
Bilinichnus
Bolonia
Bornichnus
Bunyerichnus
Calycraterion
Camborygma
Capodistria
Caprionichnius
Cardioichnus
Caridolites
Catenarichnus
Catenichnus
Chagrinichnites
Cheiichnus
Chomatichnus
Chondrites
Speciesbollensis
affinis
caespitosus
intricatus
patulus
recurvus
stellaris
targionii
GenusCirculichnis
Cladichnus
Clematischnia
Climactichnites
Cochlichnus
Compaginatichnus
Conichnus
Conostichus
Cruziana
Ctenopholeus
Curvolithus
Cycloichnus
Cylindricum
Dactyloidites
Deliatynichnis
Dendrorhaphe
Dendrotichnium
Dictyodora
Didymaulichnus
Didymaulyponomos
Diplopodichnus
Echinospira
Egoreichnis
Elingua
Enigmatichnus
Entradichnus
Epibaion
Estrellichnus
Falcichnites
Fimbritubichnus
Foveichnus
Fucoides circinatus
Fuersichnus
Funalichnus
Furculosus
Fustiglyphus
Glossifungites
Glyphichnus
Gordia
Guanshanichnus
Gyrochorte
Gyrolithes
Gyrophyllites
Haentzschelinia
Halimedides
Halopoa
Hartsellea
Heimdallia
Helicodromites
Heliochone
Helminthoida
Helminthoidichnites
Helminthopsis
Herpystezoum
Hondichnus
Hormosiroidea
Ilmenichnus
Imponoglyphus
Isopodichnus
Jamesonichnites
Katbergia
Keilorites
Kimberichnus
Koptichnus
Korymbichnus
Kouphichnium
Labyrintichnus
Lajasichnus
Lamonte
Lanicoidichna
Lennea
Lepeichnus
Lepidenteron
Liholites
Lingulichnites
Lingulichnus
Lithoplaision
Lockeia
Loloichnus
Lophoctenium
Lorenzinia
Macaronichnus
Maiakarichnus
Mammillichnis
Margaritichnus
Megagrapton
Mermia
Microspherichnus
Minterichnus
Monocraterion
Monofungites
Multilamella
Multina
Multipodichnus
Musculopodus
Naviculichnium
Nenoxites
Neoeione
Neonereites
Nereites (trace fossil)
Nummipera
Oikobesalon
Oldhamia
Olenichnus
Oniscoidichnus
Ophiomorpha
Oravaichnium
Palaeophycus
Paleodictyon
Paracanthorhaphe
Parahaentzschelina
Parapsammichnites
Parataenidium
Paratisoa
Parmaichnus
Parundichnia
Pentichnus
Petalichnus
Phoebichnus
Pholeus
Phycosiphon
Pilichnus
Piscichnus
Plagiogmus
Plangtichnus
Planispiralichnus
Planolites
Polarichnus
Polykampton
Polykladichnus
Protopaleodictyon
Protospiralichnus
Protovirgularia
Psammichnites
Psilonichnus
Pteraspisichnis
Ptychoplasma
Radiichnus
Radionereites
Rhadhostium
Rotamedusa
Rusophycus
Saerichnites
Sagittichnus
Saportia
Scalaridomus
Schaubcylindrichnus
Scolecocoprus
Scolicia
Scotolithus
Scoyenia
Selenichnites
Shanwangichnus
Sinusichnus
Skolichnus
Skolithos
Sokolovichnites
Solemyatuba
Sphaerichnus
Spirocosmorhaphe
Spirodesmos
Spirophycus
Spongelimorpha
Squamichnus
Squamodictyon
Steinsfjordichnus
Stelloglyphus
Streptichnus
Sustergichnus
Svalbardichnus
Syringomorpha
Taenidium
Tambia
Taotieichnus
Taphrhelminthopsis
Taxichnites
Teichichnus
Ternavites
Tetraichnites
Thalassinoides
Torrowangea
Transexcrementum
Treptichnus
Triacliichnis
Trichichnus
Trichophycus
Trisulcus
Tuapseichnium
Tuberculichnus
Tubichnus
Tubotomaculum
Tylichnus
Undichna
Vagorichnus
Vermichnus
Virgaichnus
Volkichnium
Walcottia
Zoophycos
unrankedTrusheimichnus
References based on distribution