Western Europe

Thus far, Early Cretaceous mammals of Western Europe are known from England (figure 2.3), Spain, and Portugal (figure 2.9). Most or all of these occurrences are older than those from the eastern part of Eurasia, being of Berriasian to Barremian age.

Britain

Early Cretaceous mammals are known from several horizons contained within two principal units in Britain, the Purbeck Limestone Group and the Wealden Supergroup. The stratotypes lie within separate depositional subbasins and they partially overlap in age. The base and top of the Purbeck are placed at the Portlandian-Berriasian (generally but not universally considered to be the Jurassic-Cretaceous boundary) and Berriasian-Valanginian boundaries, respectively. The Wealden ranges from upper Berri-asian to lower Aptian (Allen and Wimbledon, 1991; Ras-

nitsyn et al., 1998). A useful review of these strata and their mammal faunas is given by Clemens et al. (1979), from which we have drawn in preparing this account.

The Purbeck Limestone Group is often divided into two units: the Durlston Formation above (the lowest unit of which is the Cinder Member) and the Lulworth Formation below (e.g., Casey, 1963; Allen and Wimbledon, 1991). Purbeck mammals come from several horizons within the uppermost two members of the Lulworth Formation, the Marly and (overlying) Cherty Freshwater members. The depositional environment is thought to have consisted largely of mudflats along a lake with little or no salinity (e.g., Kielan-Jaworowska and Ensom, 1994). Based on current evidence, we consider all mammals of the Purbeck to be of early Berriasian age.

The first mammalian fossils from the Purbeck were collected in 1854 from the cliffs of Durlston (also called Durdlestone) Bay, Dorset (Owen, 1854). A large collection, including a number of important mammal specimens, was subsequently made by Samuel Beckles; many of these were also described by Owen (1871; see Simpson, 1928a). Several specimens were collected in later years (e.g., Willett and Willett, 1881), but the main quarry appears to be exhausted and it is in any case no longer accessible (Kermack, 1988). That quarry was in the so-called "Mammal Bed," contained within the Marly Freshwater Member of the Purbeck (Clemens et al., 1979). The exact horizon is uncertain (Kermack, 1988), but it has been linked to bed DB 83 of Clements (1993).

The mammals of Durlston Bay are of more than historical interest in that they include morphologically informative jaws and at least one partial skull. The fauna (mostly described by Simpson, 1928a) is generally similar to that of the Morrison Formation (Upper Jurassic) of North America, with one or more shared genera. There are at least 17 mammals known from Durlston Bay (table 2.9). As with the Morrison, several triconodontids and multitu-berculates are present, with docodontans and "sym-metrodontans" being less diverse and the majority of taxa being dryolestoid "eupantotherians." Notably, the common "symmetrodontan," Spalacotherium, is more derived than its counterpart in the Morrison, Tinodon (see Patterson, 1956; Cifelli and Madsen, 1999). Another notable element of the Durlston fauna is the "eupantotherian" Pera-mus, which appears to be closely related to boreosphenidan mammals (chapter 11).

In 1986, Paul Ensom began recovering vertebrate microfossils from the Purbeck through underwater screen-washing and related procedures. The mammals are almost entirely represented by isolated teeth, but the collective sample is large, including some 800 specimens. Vertebrate microfossils have been found from several localities, but currently the most important by far is Sunnydown Farm (figure 2.3) on the Isle of Purbeck, about 5 km east of Durlston Bay, near Langton Matravers, Dorset (Ensom et al., 1994). Two horizons were sampled at this site, both in the Cherty Freshwater Member of the Lulworth Formation, not far below the Cinder Bed (e.g., Sigogneau-Russell and Ensom, 1994). The mammals of Sunnydown Farm thus are slightly higher, stratigraphically, than those from Durlston Bay (see Clements, 1993).

At least 16 mammal taxa have been described or mentioned from Sunnydown Farm (see Kielan-Jaworowska and Ensom, 1992, 1994; Sigogneau-Russell and En-som, 1994, 1998; Ensom and Sigogneau-Russell, 1998, 2000; Sigogneau-Russell, 1999; Sigogneau-Russell and Kielan-Jaworowska, 2002). This approximates the diversity known from Durlston Bay, but only two genera, the "symmetrodontan" Spalacotherium and the docodontan Peraiocynodon, are shared between the two localities. On the other hand, the mammals of Sunnydown Farm strengthen links of the Purbeck fauna with those known from elsewhere. The "symmetrodontan" Tinodon and the docodontan Docodon are known from the Morrison Formation of North America. Multituberculates (Albion-baatar, Sunnyodon, Gerhardodon) share similarity, at the family level at least, with the Late Jurassic (Albionbaatari-dae,Paulchoffatiidae) and Early Cretaceous (Paulchoffati-idae, Pinheirodontidae) of the Iberian Peninsula (Hahn and Hahn, 1992, 1998a,b,d, 1999a). The aforementioned "symmetrodontan" Spalacotherium is also known from the Early Cretaceous of the Iberian Peninsula (Krebs, 1993). The bizarre "symmetrodontan" Thereuodon and early boreosphenidan mammals are shared with the Berrisian of Morocco (Sigogneau-Russell, 1994a; Sigogneau-Russell and Ensom, 1998). The "eupantotherians" Chunnelodon and Magnimus from Sunnydown Farm do not have obvious close relatives elsewhere (Ensom and Sigogneau-Russell, 1998; Sigogneau-Russell, 1999).

Most recently, mammals have been reported from two sites in the Intermarine Member of the Durlston Formation near Swanage, Dorset. These represent the strati-graphically highest mammals found to date in the Purbeck Limestone Group. One of the sites, in a quarry near Belle Vue, appears to represent a horizon laterally equivalent to beds DB 116-117 of Clements (1993). Finds reported thus far include a dentary fragment with teeth resembling deciduous premolars of a spalacotheriid and an upper molar of the dryolestid cf. Kurtodon (Ensom, 2000). The horizon of the second site, a quarry near Acton, is correlated with DB 115-116 of Clements (1993). The single specimen reported to date from Acton is a battered lower molar of the tribosphenic mammal Tribactonodon bon-fieldi (see Sigogneau-Russell et al., 2001).

table 2.9. Early Cretaceous Mammals of Britain (see figure 2.3; locality numbers do not correspond between map and table). Localities:1, Durlston Bay; 2, Sunnydown Farm; 3, Belle Vue; 4, Acton (all Purbeck Limestone Group, Berriasian); 5, Cliff End; 6, Tighe Farm (Wadhurst Formation, early Valanginian); 7, Paddockhurst Park (Grinstead Clay, middle Valanginian); 8, Isle of Wight (Wealden Group, ?Valanginian)

Docodonta

Docodontidae cf. Docodon sp. (2) Peraiocynodon inexpectatus (1, 2) Multituberculata Albionbaataridae

Albionbaatar denisae (2) Eobaataridae

Loxaulax valdensis (5) Loxaulax sp. (8) Paulchoffatiidae

Sunnyodon notleyi (2) Pinheirodontidae

Gerhardodon purbeckensis (2) Plagiaulacidae

Bolodon crassus (1) "Bolodon" elongatus (1) Bolodon falconeri (1) Bolodon minor (1) Bolodon osborni (1) Plagiaulax becklesii (1) Eutriconodonta Triconodontidae

Triconodon mordax (1) Trioracodon ferox (1) Trioracodon major (1) Trioracodon oweni (1) Family incertae sedis

Gen. et sp. indet. A (2) Gen. et sp. indet. B (2) Archaic "symmetrodontans" Thereuodontidae

Thereuodon taraktes (2)

Tinodontidae

Tinodon micron (2) Family incertae sedis Gen. et sp. indet. (2) Stem Trechnotheria Spalacotheriidae

Spalacotherium tricuspidens (1, 2, 6) Spalacotherium taylori (7) Spalacotherium evansae (2) Gen. et sp. indet. (3) Stem Cladotheria ("eupantotherians") Dryolestidae

Amblotherium pusillum (1) Kurtodon pusillus (1) cf. Kurtodon sp. (3) Laolestes hodsoni (5, 6) Peraspalax talpoides (1) Phascolestes mustelulus (1) Paurodontidae

Dorsetodon haysomi (2) Peramuridae

Peramus tenuirostris (1) Family incertae sedis

Chunnelodon alopekodes (2) Magnimus ensomi (2) Stem Boreosphenida ("tribotherians") Aegialodontidae

Aegialodon dawsoni (5) Family incertae sedis

Tribactonodon bonfieldi (4) Gen. et sp. indet. (2)

Initial discoveries of mammals in the Wealden of Britain date to the latter part of the nineteenth and early twentieth centuries and include only three specimens (see Simpson, 1928a). In the 1960s, investigations by Kermack, Clemens, and colleagues resulted in a substantial improvement to the meagre record from the Wealden. Like the Purbeck Group, the Wealden was deposited in a number of subbasins across Western and Central Europe, but thus far mammals are known only from exposures in southern England. Correlation of the Wealden is discussed by Allen and Wimbledon (1991), and mammal occurrences and their stratigraphic context are summarized by Clemens et al. (1979, and references cited therein). In the Wealden subbasin, which includes most of the mammal localities, the basal Wealden overlaps with the uppermost Purbeck. The Wealden has two major divisions, the Hastings Beds (below) and the Weald Clay (above). All mammal sites lie within the Hastings Beds, which span the upper Berriasian through the Valanginian-Hauterivian boundary. In turn, the Hastings Beds include (from lowest to highest) the Ashdown Formation, the Wadhurst Formation, the Lower Tunbridge Wells Formation, the Grinstead Clay (locally), and the Upper Tunbridge Wells Formation.

The most diverse assemblage of Wealden mammals is from Cliff End (figure 2.3). The site is on the coast near Hastings (its name in older literature) and is the source for the first mammals known from the unit (e.g., Woodward,

1911). Cliff End is in the Wadhurst Formation and is of early Valanginian age. Four mammals are known from Cliff End (table 2.9). Of these, the "symmetrodontan" Spalacotherium tricuspidens is also known from the Purbeck, and the "eupantotherian" Melanodon is recorded from the Morrison Formation of the western United States. The most celebrated mammal from Cliff End is Ae-gialodon dawsoni, represented by a lower molar with a basined heel—that is, the tribosphenic design seen in marsupials and placentals (Kermack et al., 1965). For many years Aegialodon was the oldest known tribosphenic mammal, until the discovery of boreosphenidans from the Berriasian of Morocco and Britain (Sigogneau-Russell, 1991a, 1992; Sigogneau-Russell and Ensom, 1994).

The remaining three mammal sites in the Wealden have each yielded only one or two taxa. Tighe Farm, northeast of Cliff End, is also in the Wadhurst Formation (lower Valanginian) and shares the "eupantotherian" Melanodon hodsoni with that site. Paddockhurst Park, Sussex, is in the Grinstead Clay, which is stratigraphically higher than Cliff End and Tighe Farm. Judged by the correlations presented in Allen and Wimbledon (1991),Pad-dockhurst Park is probably of middle Valanginian age, somewhat older than suggested by Clemens et al. (1979). The "symmetrodontan" Spalacotherium is represented here by S. taylori (known only from the Wealden), rather than S. tricuspidens, which is found in both the Purbeck and the lower Wealden. Lastly, the multituberculate Lox-aulax, also known from Cliff End, has been reported from a site in the Wealden on the Isle of Wight (Butler and Ford, 1977). The mammal specimens come from one of three lignitic claystones; unfortunately, there is no published information as to the stratigraphic placement of the site relative to others in the Wealden.

Spain and Portugal

Three sites on the Iberian Peninsula have yielded substantial remains of mammals from the latest Jurassic or Early Cretaceous; two others have yielded isolated teeth or single specimens (table 2.10). Most were developed by personnel of the Freie Universität Berlin, initially under the leadership of Walter Kühne and continued by Siegfreid Henkel, Bernard Krebs, and colleagues (see brief account in Krebs, 1980). The geologically oldest of these is Porto Pinheiro (sometimes referred to as Porto Dinheiro), on the coast near Lourinha, Portugal (figure 2.9). The age of the site, which is in the Lourinha Formation, is not well understood; it may be Late Jurassic or Early Cretaceous. Palynomorphs, which indicate a well-differentiated flora and a fluvial setting, suggest a Tithonian-Berriasian age table 2.10. Early Cretaceous Mammals of the Iberian Peninsula (Spain and Portugal; see figure 2.9; locality numbers do not correspond between map and table). Localities: 1, Porto Pinheiro (?Berriasian, Portugal); 2, Pié Pajarón; 3, Galve; 4, Uña (all early Barremian, Spain); 5, Vallipón (late Barremian, Spain)

table 2.10. Early Cretaceous Mammals of the Iberian Peninsula (Spain and Portugal; see figure 2.9; locality numbers do not correspond between map and table). Localities: 1, Porto Pinheiro (?Berriasian, Portugal); 2, Pié Pajarón; 3, Galve; 4, Uña (all early Barremian, Spain); 5, Vallipón (late Barremian, Spain)

Eutriconodonta

Pinheirodon pygmaeus (1)

Gobiconodontidae

Pinheirodon vastus (1)

Gobiconodon sp. nov. (5)

Pinheirodon sp. (1)

Triconodontidae

Archaic "symmetrodontans"

Priacodon sp. (1)

Family incertae sedis

Multituberculata

Gen. et sp. indet. (5)

Family incertae sedis

Tinodontidae

Gen. et sp. indet. (5)

?Tinodon sp. (1)

Eobaataridae

Stem Trechnotheria

Eobaatar hispanicus (S, 4)

Spalacotheriidae

?Eobaatar pajaronensis (2)

Spalacotherium henkeli (3)

Parendotherium herreroi (S)

Stem Cladotheria ("eupantotherians")

Gen. et sp. indet. (5)

Dryolestidae

Paulchoffatiidae

Crusafontia cuencana (3, 4)

Galveodon nannothus (S, 4)

Laolestes andresi (1)

Gen. et sp. indet. (5)

Portopinheirodon asymmetricus (1)

Pinheirodontidae

Peramuridae

Bernardodon atlanticus (1)

Nanolestes krusati (1)

Ecprepaulax anomala (1)

Family incertae sedis

Iberodon quadrituberculatus (1)

Gen. et sp. indet. (5)

Lavocatia alframbrensis (S)

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