T08 



PALEONTOLOGY 



Palaotoie Lift. The most prominent tj ( of 

 Pabroxoic time* were Graptolites, Kugofte rural*, 

 Brachio|Nids. Ciinoids, Pterojiods, Nautilid Ccpha- 

 III|HX|, Tiiliihites. Kuryptcrids, ami HfltOTMsrad 

 (.ainnd-. (iiaploliu* ranged from the ('aiiihriiui 

 into the I/ower Old Ked Sandstone, hut attained 

 llicir iimxiiiiiini in Lower Silurian times. Rugose 

 corals, unknown in the Cambrian, swarmed in 

 Silurian, Devonian, and Carlioniferous seas, luit 

 were much lew numerous in those of the Per- 

 ini.in. Crinoids lirst ap|>ear in the ( amlirinn, are 

 unmet. ms in Silurian ami Devonian rocks, hut 

 more abundant still in tlie ('argilliferous. After 

 tiiis they Ix'gin to decline. Brachiopods, com- 

 mencing in the Cambrian. aUiundrd all through 

 P.il.eo/oic times, luit culminated in the rppcr 

 Silurian jieiiod. They were still numerous in 

 Devonian and Carhnnifenms neon, hut less iilmn- 

 l.mi in those of the I'ennian period. Ptero|Mids 

 were more coin mon in Upper ( 'ainhrian and Silurian 

 than during Devonian and Carlioiiiferous times. 

 Nautilid Cephalopoda first ap|>car in the Upper 

 Cambrian, and seem to culminate in the Silurian. 

 but they roiitinue<l to aliound in the Devonian and 

 Carhonifei'ouH seas, becoming reduced in those of 

 the Permian (iciiod. Trilobitcs appear first in the 

 r.ini!,ii ,n. reach a maximum in the Silurian, wane 

 in the Devonian and Carboniferous, and die out in 

 the Permian. They are therefore essentially and 

 characteristically Paheozoic forms. So likewise 

 Are the Euryptends, which, culminating apparently 

 in the (JppW Silurian and Old Hed Sandstone, 

 became extinct in Carlxmifenius times. Ganoids 

 with heterocercal tails first appear in I'pper Silu- 

 rian strata, and reach their niaximiuu in the Old 

 Red Sandstone. The great order of Sharks and 

 llays likewise Antes bock to Upper Silurian times. 

 Such are the more prominent types in Paln'o/oic 

 strata. Many other forms, however, are met with, 

 which may be noted starfishes (Aster- 



oiilea), brittle-stars (Opliiuroidea), sea urchins 

 ( Kchinoidea), and the wholly extinct and char- 

 acterUtic Paheo/nic types, Cysioidea ami Blast- 

 oid<-a. .\mongxt the Crustacea were cirripedes, 

 oMtracods, phyllopods, king-crali, Unpmpoib, 

 iso|N>ds, long-tailed decapods, and liomapoda, 

 Arachnids were represented by scorpions ami other 

 I'm ins ; myriapodH and insects by a numlier of an- 

 central types. All the great classes of ntollnscan 

 life were present Cephalopoda appealing first in 

 the Upper Canihrian ; Ptcro|>ods in Lower Cam 

 brian ; Gasteropoda in Lower Silurian ; and 

 Lamellibranchs in Upper Canihrian. The fishes 

 have been already mentioned. Alupbibiana, n-pn- 

 tented by Lahyrinthodont* and iSalamandrouls, 

 ap|H-ai first in CarlxmifprouR strata. 



Amongst plants the prominent Pala-o/oir types 

 are rrvpto^ams I.epiiliKlemlroiils, Si<.'illariiiiiU. 

 and Calamitcs bein^ exclusively I'alivozoic, but 

 conifers were ahui |.i.--i-nt. 



It may l>e notiil that many of the characteristic 

 life forum of I'aheozoii- times were what are termeil 

 tynthttir or r<iin/irr/iriijtiff ty|Mi, that is t> say, 

 t\|H-< which while helon^in^ fundamoiitally to some 

 paitii-iilui division or uroupof the animal Kingdom, 

 yet present in their structure characteristics .,f one 

 or more contin|>orancouH, or an yet mm existinx 

 types. Amoii); such intermediate or comprehen- 

 sive form* may !" mentioned the LabyiintbodoBta, 

 which were urmleh- aniphihiaiis with many pi-.-ine 

 and reptilian charuc-i.>. i-ii. -. K\ainples are also 

 iiiimsbisl liv the (i.uioi.ls. the TrilohiteK, the 

 HrarhinfKxU. the inMM-U, \c. Amount plants the 

 Lepidmlpiiilroiiln exhihit similar peculiarities, for 

 tln-y combine characteristics of club-mosses and 

 conifer*. A(,'ain. many I'al.-ro/.oic forms altaincil 

 a larger size than the corre|>ondiiiK fonns that 

 tu Jater times. Thus, some of the ptcro- 



|*ls, cephalopls, ostraciKls, phyllopiHls, and in- 

 sects wi-ie larger than an\ i-oiresjiondiii); fonns of 

 our own day. The amphibians likewise exceedi-il 



B any living representatives of thei, . 

 Iniiumerahlc 1'uhro/oic genera died out iK'fore 



.oil' times, while not a few lived on, ami some 

 have even |>ersistcd to the pivsent day. Tin se 

 |>ersistent forms are met with ehielly itmong the 

 lower t\ IK'S of animal life, as foriuninifers, hrachio- 

 |MK|S, and niolluBcs. See CAMBRIAN, SlI.ntlAX, 



oi.u KKIJ SANDSTONE, CARBOSIKEROUS, and I'KK- 

 MIAN SYSTEMS. 



Me-tozoic Life. The life of Mcsozoic times is in 

 many respecU strongly contrasted with that of the 

 I'ahfozoic era. In place of Si^illarioids and I.epido- 

 dendroids, the prevalent forms of plant-life up 

 to the close of tlie Cretaceous period were arboies- 

 cent and herbaceous ferns, conifers, ami cycads, 

 while in late Cretaceous times the earliest angio- 

 s-IK-riiis appeared. Corals, which were plentiful in 

 Mesozoic seas, consisted almost exclusively of 

 modern types the rugose corals having waned 

 almost to extinction. Echinoids and starfishes 

 alxmmlcil, but Crinoids, so prevalent in Paln-ozoic 

 seas, were now much reduced in numliers. Some 

 of tlie higher grades of the Crustacea, which are 

 hardly known in I'ahco/.oic rocks, were plentiful in 

 Mesozoic times, and the same was the case with 

 insects. Brochiopods ceased now to be dominant 

 forms; while amongst molluscs the Cephalopoda 

 take the lead, and reach their culmination in 

 swarms of Amnmnitida' and lielemnitidae. Gas- 

 teropoda and Lamellihranchs are well represented, 

 and include a numlier of modern genera, which 

 increased towards the close of the era. Ganoid* 

 were still numerous, mostly with symmetrical 

 tails. Chimteroids, true sharks, and rays were all 

 represented, while Teleosteans or hoiiy iishcs made 

 their first appearance. Lahyrinthodonts, which in 

 Triossic times attained a great si/e. soon died out, 

 making way for the advent of a prodigious rejitilian 

 fauna, in which all orders, save tlie OphwiaM, 

 were represented. There were swimming reptiles 

 (Ichthyosaurus, q.v., Plesiosaurus, <|.v.), Hying 

 reptiles ( Pterodactylus, q.v.), snake-like reptiles 

 (Dinosaurs, see DINOSAVRIA), crocodiles, and chel- 

 oniaiis. This reptilian life was specially abundant 

 in Jurassic times, liinls probably were numerous, 

 some of the forms being toothed, while others may 

 have approximated to modern tyjies. Mammals 

 were represented by only the inferior grade of 

 marsupials, and were all of small size. All the 

 remarkable reptiles referred to became extinct 

 before the beginning of the Cainozoic era. So 

 it was with the characteristic Meso/.oic niollns- 

 cau families of Ammonitiihe, Itclemnitidiv, and 

 Ilippiiritidie. Putting aside the lowly oiganised 

 Protozoa, it may he said that hardly one Cretaceous 

 sjiecies has lieen met with in Caimi/oie or Tertiary 

 strata. See TiiiAssic, JURASSIC, and CRETACKOI s 

 SYSTEMS. 



<',,,,,,,ziiir Lift.- The plants of early Caino/.oic, 

 times, although ilitlering Kpc<-ilically and often 

 genetically from living forms, vet approach on the 

 whole to "existing types. Palms were a common 

 feature of the norax from Koeene into Pliocene 

 times. Indo-Australian types were common in 

 K.mo|H> during the early Kocenc. but later on 

 forms characteristic of the warmer latitude* of 

 North America liegan to abound. A commingling 

 of Indo-Anstralian and American t\ pes also marUed 

 the < IligcM'ene ]ieri<Kl. hut the American forms 

 gradually increased until in Miocene times they 

 prc]M>nderatcd over nil the others. The Pliocene 

 flora of central Knrope had a prevalent Mediter- 

 ranean character. With regard to the lower foim- 

 of animal life, all that need lie noted here is the 

 general fact that these have a modern aspect, the 



