Dineley, D. & Metcalf, S. GCR Editor: D. Palmer. 1999. Fossil Fishes of Great Britain. Geological Conservation Review Series No. 16. JNCC, Peterborough, ISBN 1 86107 470 0.
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A rich fossil fish fauna has been derived from foreshore exposures of the Aldwick Beds (London Clay, Division B) at Bognor Regis in West Sussex. The preservation is excellent and many type specimens of teleost otoliths have been described.
The foreshore exposures of London Clay Formation at Bognor Regis have yielded a finely preserved vertebrate fauna, including land-derived mammals and reptiles, and shark and teleost debris, occurring mainly as teeth, scales, otoliths and bones, mostly from three horizons in the Aldwick Beds' (Division B of King, 1981). The vertebrate remains can be recovered from the outcrops on the foreshore, or frequently from pyritous debris pools on the shoreline that concentrate the scattered fossil material. Many species of elasmobranch and teleost fishes have been recovered by bulk processing the sediments and beach sands, although in more recent years coastal protection schemes have diminished the exposure.
Much of the early work on the London Clay at Bognor focused upon the palaeontology, and limited descriptions include those of Dixon (1850) and Reid (1897). Venables (1929, 1963) produced the most detailed account of the geology and the succession of beds exposed along the shoreline, and also produced descriptions of the insect fauna recovered from the 'Beetle Bed' (London Clay, Division B; Venables and Taylor, 1963). Subsequent work by King (1981) has focused on the stratigraphy and the site is also designated as an SSSI for Tertiary stratigraphy in the GCR volume by Daley and Balson (1999).
The fish fauna was listed by Venables (1963), and components of it have subsequently been described by Casier (1966); elasmobranchs) and Stinton (1965c, 1971; teleost otoliths).
The London Clay Formation exposed along the coast from Bognor westwards to Aldwick and Pagham comprises intermittent foreshore outcrops of silty muds and sands, which dip at a low angle towards the south-west. The following composite section is taken from the description of the sequence by Venables (1963), with additional information on the formal stratigraphical nomenclature of beds from King (1981):
| Thickness (m) | |
| London Clay Formation, Division C (of King, 1981) | |
| 5. Upper Clay (of Venables, 1963) | |
| Undescribed deposits | 6.1 |
| Grey clay with plant remains | 0.9 |
| Undescribed deposits | 3.5 |
| Pagham Rock | 0.6 |
| Clay (partly described, sparsely fossiliferous) | 18.6 |
| Cainocrinus Bed | 1.2 |
| Pholadomya Bed | 0.6 |
| Clay, partly described, with basal glauconitic pebble bed | 3.7 |
| London Clay Formation, Division B (of King, 1981) | |
| 4. Barn Rock Bed (of Venables, 1963) | 2.4 |
| 3. Middle Clay (of Venables, 1963) | |
| Base of Barn Rock | 1.2 |
| Undescribed deposits | |
| Craigwell Bed | 1.5 |
| Undescribed deposits | 3.0 |
| 3.3. Upper Aldwick Beds (of Venables, 1963) | |
| Clay with pyritized plant remains | 2.4 |
| Two septarian bands | 0.6 |
| Clay with pyritized plant remains | 1.2 |
| Septarian band (with Artica planata in clay) | 0.3 |
| Upper Fish-Tooth Bed | 1.5 |
| 3.2. Clay, unfossiliferous, with septarian band 1 m above base | 3.7 |
| 3.1. Lower Aldwick Beds (of Venables, 1963) | |
| Beetle Bed. Clay with septarian band | 1.2 |
| Lower Fish Tooth Bed. Earthy clay, with clay pellets and basal black flint pebble bed | 0.6 |
| London Clay Formation, Division A3, Bognor Member (of King, 1981) | |
| 2. Bognor Rock Group (of Venables, 1963) | |
| Bognor Rock Bed. Interbedded unconsolidated grey sand and partially cemented, fine glauconitic sandstone | 6.7 |
| Sandy clay, and soft sandstone | 3.0 |
| London Clay Formation, Division A2, Walton Member (of King, 1981) | |
| 1. Lower Clay (of Venables, 1963) Septarian band, with white clay, iron stained | 0.6 |
| 'Cyprina' Bed | 5.5 |
| Starfish Bed | 1.8 |
| Clay | 1.2 |
| Astarte Bed | 2.4 |
| Friable clay | 2.7 |
| Clay with occasional pyritized plant remains | 2.7 |
| Sandy layer | 0.3 |
| Clay, partly described | 4.6 |
| Septarian band, with white clay, iron stained | 0.3 |
| Dark grey, silty clay | 0.6 |
| Deposits obscured by alluvium | 3.0 |
Over 90 m of London Clay is exposed along the Bognor coastline (King, 1981). King (1981) recognized 3 m of the Oldhaven Formation (the London Clay Division A1 being apparently absent; Daley in Daley and Balson, 1999) beneath beach sand at the eastern end of the section. The junction between the London Clay and the overlying Bracklesham Group is unexposed (Daley in Daley and Balson 1999).
The fish assemblage occurs almost exclusively in the Aldwick Beds of the London Clay Division 3, although Venables (1963, pp. 259–60) records the teleost Cylindracanthus rectus (Dixon) from the Starfish Bed of Division A3. Division B of King (1981) has a varied fauna and flora, much of which is preserved in pyrite. The invertebrate Fauna of the fossiliferous horizons, a silty clay rich in molluscan shell debris, is somewhat dif-Ferent from that of the typical London Clay. Pyrite also occurs abundantly as small grains and nodules thoughout Division B. Amongst the pyritized fossils are insects and beetles (Britton, 1960; Venables and Taylor, 1963), that occur in association with a large assemblage of land-derived seeds and fruit, and fish remains, in the Foreshore exposures of Divisions B1 and B2 (King, 1981, p. 73). Although fish remains can De recovered directly from the fossiliferous units, when these are exposed at low tide, some of the best material is found in the natural concentrates of pyritic debris or 'pyrite pools', and the beach sand can itself be sieved for tiny fish teeth and otoliths. Fish material from these accumulations is invariably disarticulated, but the preservation is very good
The fauna listed below is recorded from the classic work of Venables (1963) and lists in Casier (1966) and Ward (1980). Otoliths from this locality have been studied by Stinton (1957, 1965c, 1975–1980).
Chondrichthyes: Elasmobranchii: Neoselachii: Squalomorphii
Heterodontus sp.
Isistius trituratus (Winkler, 1874)
Notorhynchus serratissimus (Agassiz, 1844)
Squalus minor (Leriche, 1902)
Chondrichthyes: Elasmobranchii: Neoselachii: Squatinomorphii
Squatina prima (Winkler, 1874)
Chondrichthyes: Elasmobranchii: Neoselachii: Galeomorphii
Anomotodon sheppeyensis (Casier, 1966)
Carcharias hopei (Agassiz, 1843)
Carcharhinus (Hypoprion)sp.
Galeorhinus lefevrei (Daimeries, 1891)
G. formosus Arambourg, 1952
Heterodontus vincenti (Leriche, 1905)
H. wardenensis Casier 1966
Isurolamna affinis (Casier, 1946) ( = Lamna affinis, L. inflata)
Isurus praecursor (Leriche, 1905)
Jaekelotodus trigonalis (Jaekel 1895)
'Lamna' lerichei (Casier, 1946) ( = L. vincenti)
Odontaspis winkleri (Leriche, 1905)
Otodus obliquus Agassiz, 1836
Oxyrhina sp.
Physogaleus secundus (Winkler, 1874) ( = Physodon secundus, P. tertius, Galeorhinus minor)
Scyliorhinus gilberti Casier, 1946
'Scyliorhinus'minutissimus (Winkler, 1873)
'S. biauriculatus (Casier, 1950)
Synodontaspis macrotus (Agassiz, 1843)
S. robustus (Leriche, 1905)
Chondrichthyes: Elasmobranchii: Neoselachii: Batomorphii
Burnhamia (Rhinoptera)daviesi (Woodward, 1889)
Dasyatis duponti (Winkler, 1874)
D. tricuspidata Casier, 1946
Myliobatis dixoni Agassiz, 1843
M. toliapicus Agassiz, 1843
Myliobatis sp.
Raja sp.
Chondrichthyes: Holocephali: Chimaeriformes
Elasmodus hunteri Egerton, 1843
Chimaera sp.
Osteichthyes: Actinopterygii: Teleostei: Elopomorpha
Albula oweni Leriche, 1905
Osteichthyes: Actinopterygii: Neopterygii: Euteleostei
Cylindracanthus rectus (Dixon, 1850)
Egertonia isodonta Cocchi, 1866
Eutrichiurides winkleri Casier, 1946
Palaeogadus (Trichiurides) sagittidens (Winkler, 1874)
Sciaenurus bowerbanki Agassiz, 1845
Scomberomorus sp.
Sphyraena sp.
Undifferentiated 'teleosts'
Siluroid spine, cf. Arius sp.
Pseudosphaerodon sp.
Platylaemus sp.
Glyptorhynchus sp.
The fish-bearing horizons within the Aldwick Beds of the London Clay at Bognor Regis represent deposition within a nearshore marine environment at the eastern edge of the Hampshire Basin. Depths of less than 70 m have been postulated by Hewitt (1988a, 1988b) based upon his studies of nautilid fossils. A nearshore environment is also suggested by the abundance of well-preserved insect and beetle material (Jarzembowski, 1991) and drifted plant matter (Chandler, 1964). The Bognor assemblages suggest that the palaeoclimate was similar to the humid, subtropical conditions of the Mediterranean (Collinson, 1983).
The list of fossil fishes is impressive, with 34 species of elasmobranchs, two holocephalians and 21 species of actinopterygians (and 26 species of otoliths) at least. In an inshore environment, as is suggested here, the possibility of occasional catastrophic mixing of vertebrate remains from different habitats cannot be ruled out. This might account for the diversity and richness of the fauna. Nevertheless, the vertebrates of the nearshore neritic zone would have occupied a wide variety of ecological niches, as is borne out by the range of taxa present. The large number of predatory elasmobranchs is witness to the high productivity of the local waters, and the range of teleosts suggests a variety of feeding patterns at several levels within the broad trophic pyramid. Populations were probably very high per unit area of the depositional basin, again this is consistent with the postulated subtropical (Mediterranean-like) conditions.
Similar London Clay, Division B, faunas have been recovered from Alum Bay and Whitecliff Bay
The foreshore exposures of London Clay, Division B, at Swalecliff, Kent
Bognor Regis is the only locality in the Hampshire Basin to produce fossil fish material from the London Clay Formation, Division B, in any quantity, thus its conservation value. The fossiliferous horizons can still be sampled at beach exposures, should produce more material.