﻿EXTINCTION 
  AND 
  EXTERMINATION 
  TOLMACHOFF 
  271 
  

  

  no 
  enemies 
  outside 
  of 
  their 
  own 
  stock, 
  such 
  as 
  menaced 
  the 
  trilobites. 
  

   The 
  low 
  mentality 
  of 
  the 
  herbivorous 
  species 
  was 
  confronted 
  with 
  

   the 
  similar 
  low 
  mentality 
  of 
  their 
  carnivorous 
  enemies. 
  Reference 
  

   to 
  the 
  simultaneous 
  existence 
  of 
  more 
  intelligent 
  archaic 
  mammals 
  

   is 
  not 
  significant, 
  for 
  these 
  small, 
  weak 
  animals 
  used 
  their 
  higher 
  

   intelligence 
  or 
  cunning 
  to 
  protect 
  themselves 
  from 
  their 
  enemies 
  

   rather 
  than 
  to 
  harm 
  these 
  gigantic 
  reptiles, 
  much 
  less 
  to 
  cause 
  their 
  

   extinction. 
  In 
  fact, 
  in 
  the 
  opinion 
  of 
  many 
  paleontologists 
  the 
  rela- 
  

   tions 
  were 
  exactly 
  opposite 
  — 
  that 
  is, 
  the 
  mammalian 
  evolution 
  was 
  

   handicapped 
  by 
  the 
  domination 
  of 
  reptiles, 
  forming 
  "an 
  overwhelm- 
  

   ing 
  check 
  against 
  which 
  these 
  small 
  creatures 
  could 
  not 
  contend."® 
  

   In 
  the 
  opinion 
  of 
  Osborn, 
  only 
  the 
  dying 
  out 
  of 
  the 
  large 
  reptiles 
  

   "prepared 
  the 
  way 
  for 
  the 
  evolution 
  of 
  the 
  mammals. 
  "^° 
  The 
  

   extinction 
  of 
  the 
  gigantic 
  land 
  reptiles 
  has 
  also 
  been 
  explained 
  as 
  a 
  

   consequence 
  of 
  a 
  change 
  of 
  climate. 
  The 
  cooling 
  of 
  the 
  climate 
  and 
  

   the 
  obliteration 
  of 
  their 
  homes 
  in 
  the 
  swamps 
  bordering 
  the 
  inland 
  

   seas 
  might 
  have 
  had 
  a 
  disastrous 
  effect 
  on 
  the 
  large 
  beasts 
  of 
  Creta- 
  

   ceous 
  time,^^ 
  provided 
  that 
  this 
  change 
  had 
  taken 
  place 
  rapidly; 
  but, 
  

   in 
  the 
  usual 
  slow 
  course 
  of 
  geological 
  processes, 
  dinosaurs 
  had 
  plenty 
  of 
  

   time 
  to 
  migrate 
  to 
  more 
  favorable 
  regions 
  or 
  to 
  become 
  adapted 
  to 
  

   new 
  conditions. 
  

  

  It 
  has 
  been 
  said 
  that 
  the 
  climatic 
  changes 
  that 
  contribute 
  to 
  the 
  

   extinction 
  of 
  one 
  race 
  at 
  the 
  same 
  time 
  contribute 
  to 
  the 
  evolution 
  

   of 
  another. 
  ^^ 
  It 
  might 
  therefore 
  be 
  supposed 
  that 
  some 
  dinosaurs 
  

   would 
  have 
  survived, 
  even 
  if 
  the 
  main 
  stock 
  had 
  been 
  completely 
  

   destroyed. 
  In 
  the 
  opinion 
  of 
  Lull, 
  "one 
  of 
  the 
  most 
  inexplicable 
  of 
  

   events 
  is 
  the 
  dramatic 
  extinction 
  of 
  this 
  mighty 
  race. 
  " 
  ^^ 
  Con- 
  

   cerning 
  sauropods 
  he 
  writes: 
  "We 
  know 
  of 
  no 
  reason, 
  other 
  than 
  

   racial 
  old 
  age 
  or 
  a 
  restriction 
  of 
  their 
  peculiar 
  habitat, 
  for 
  their 
  

   extinction." 
  ^* 
  As 
  has 
  just 
  been 
  explained, 
  the 
  restriction 
  of 
  habitat 
  

   can 
  not 
  be 
  considered 
  an 
  effective 
  cause. 
  Especially 
  is 
  this 
  true 
  in 
  

   relation 
  to 
  the 
  reptiles 
  that 
  lived 
  in 
  "the 
  most 
  constant 
  of 
  all 
  organic 
  

   habitats, 
  "^^ 
  the 
  sea, 
  where 
  climatic 
  conditions 
  would 
  necessarily 
  

   have 
  been 
  much 
  less 
  noticeable 
  and 
  the 
  animals 
  could 
  have 
  adapted 
  

   themselves 
  to 
  new 
  conditions 
  more 
  readily 
  than 
  on 
  land. 
  But 
  the 
  

   Mesozoic 
  reptiles, 
  in 
  the 
  sea 
  as 
  well 
  as 
  on 
  the 
  land, 
  died 
  out 
  completely 
  

   It 
  may 
  be 
  that 
  their 
  low 
  mentality, 
  which 
  may 
  be 
  compared 
  to 
  that 
  

   of 
  the 
  present-day 
  fishes, 
  was 
  not 
  so 
  great 
  a 
  handicap 
  as 
  the 
  corre- 
  

   spondingly 
  low 
  mentality 
  of 
  the 
  land 
  reptiles. 
  

  

  ' 
  R. 
  S. 
  Lull, 
  Organic 
  evolution, 
  p. 
  547. 
  

  

  1" 
  H. 
  F. 
  Osborn, 
  The 
  age 
  of 
  mammals, 
  p. 
  97. 
  

  

  '■ 
  Charles 
  Schuchert, 
  Historical 
  geology, 
  p. 
  497. 
  

  

  " 
  R. 
  S. 
  Lull, 
  Organic 
  evolution, 
  p. 
  690. 
  

  

  " 
  Idem, 
  p. 
  531. 
  

  

  " 
  Idem, 
  p. 
  517. 
  

  

  '•' 
  Charles 
  Schuchert, 
  Historical 
  geology, 
  p. 
  7. 
  

  

  