How large should whales be?

0.26 MB·

by  Aaron Clauset

How large should whales be?
Aaron Clauset1,2,3,∗
1Department of Computer Science, University of Colorado, Boulder CO, 80309 USA
2BioFrontiers Institute, University of Colorado, Boulder CO, 80303 USA
3Santa Fe Institute, Santa Fe NM, 87501 USA
Theobservedbodymassesforallextantcetaceanspecies,includingthe175,000,000gBlueWhale,
are predicted, with no tunable parameters, by a macroevolutionary tradeoff between short-term
selectiveadvantagesand long-term extinctionrisks from increased species bodysize, unfoldingin a
pelagic environment. Dramatic size differences between terrestrial and aquatic mammals are thus
the result of increased convective heat loss is water, which induces a minimum viable size orders
of magnitude larger than the 2g limit induced by air for terrestrial mammals. The large minimum
sizewouldhavepresentedahighmacroevolutionarybarriertomammalsbecomingfullyaquaticand
2 explains thehistorical timing of mammals’ invasion of aquatichabits.
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0 Keywords: bodymassdistribution,cetaceans, macroevolution, cladogenesis
2

l
u Cetaceans include the largest animals ever to live, in- size (among other reasons [24]) suggest that this theory
J cluding the Blue Whale (Balaenoptera musculus),which may be flawed.

5 is nearly 30 times larger than an African elephant and Here,weconsiderthebodymassesofcetaceans,which
twice as large as the largest sauropod. However, the also exhibit the canonical right-skewed pattern (Fig. 1):

] evolutionary and ecological reasons for their enormous the median size (356kg, Tursiops truncatus) is close to
E
sizes or the possibility of still largeranimals remains un- thesmallest(37.5kg,Pontoporia blainvillei)butfarfrom
P
clear. A deeper understanding of the mechanisms shap- the largest (175,000kg). This fact is notable because
.
o ing cetacean sizes would shed light on the interaction of Cetaceaisamodest-sizedclade(77extantspecies)within
bi macroecological[7]andmacroevolutionaryprocesses[44], Mammalia and claims about canonical size distributions
- on long-term trends in species mass [3, 4], e.g., Cope’s haveprimarilybeenmadeaboutmuchmorespecioseand
q rule,theempiricallyobservedtendencyforspeciesmasses higher-leveltaxonomic groupings. Furthermore,Cetacea
[
toincreasewithinalineageoverevolutionarytime[2,43], is the largest and most diverse aquatic mammal clade

1 and may inform conservation efforts. (Sireniahasonlyfiveextantspecies). Cetaceansizesthus
v Manymajoranimalclades,including mammals,birds, provide a unique test of the macroevolutionary trade-
8
fish and insects, seem to exhibit a canonical pattern in off hypothesis. They allow us to test whether the same
7
4 the distribution of species masses [1, 10, 24, 43]. For ex- short-term-long-term tradeoff that explains the sizes of
1 ample, the most common size of a terrestrial mammal terrestrialmammalsalsoexplainthe sizesofwhales,and
. is roughly 40g (common Pacific Rat, Rattus exulans). to investigate the impact of an aquatic environment on
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Both larger and smaller species are much less common, mammalian body size evolution.
0
2 but asymmetrically so: the largest species, like the ex-
1 tinctImperialMammoth(Mammuthusimperator,107g),
: are orders of magnitude larger, while the smallest, like
v 103
i Remy’sPygmyShrew (Suncus remyi, 2g),areonlyalit- terrestrial mammals
X tle smaller (Fig. 1). aquatic mammals
r
a Both the precise shape and the origins of its ubiq-
uity have long been a topic of ecological interest. Re- 102
y
cently,thischaracteristicpatternwasshowntobealong- nc
e
termconsequencewhenaminimumviablebodysize,e.g., u
q
farotmrapdheoyffsiobloegtwiceaelnorsthhoerrtm-toerrmeguslealteocrtyivleimaidtsv,acnotnagstersai[n7s] Fre101
and long-term extinction risks from increased species
size [10, 11] (Fig. 2a). Other studies have suggested
thatthepatterniscausedbycompetitionaboutataxon-
100
specific energetically optimal body size [8, 26, 39]; how- 100 101 102 103 104 105 106 107 108
ever, evidence of Cope’s rule—descendant species tend Species body mass (grams)
tobelargerthantheirancestors—andthefactthatmost
species are not close to their group’s predicted optimal FIG. 1: Terrestrial (includes semi-aquatic) [40] and fully
aquatic mammal species mass distributions. Both show the
canonical asymmetric pattern: the median size is flanked by
a short left-tail down to a minimum viable size and a long
∗Electronicaddress: [email protected] right-tail out toa few extremely large species.
2
We show that the tradeoff mechanism is universal for
mammals. Using a cladogenetic diffusion model esti- A
smallest largest
mated from fossil and extant terrestrial mammal data,
but with a minimum viable size appropriate for aquatic
Long-term
endotherms, we produce a statistically accurate, zero- extinction risks
parameter prediction of extant cetacean masses. This
strongagreementimpliesthatasinglemacroevolutionary
tradeoff explains both aquatic and terrestrial mammal
sizes. We close with a brief discussion of the ecological Lower
boundary Short-term
and evolutionary theoretical implications. effects selective advantages
I. NEUTRAL MODEL FOR CETACEAN SIZES
FollowingClausetandErwin[10],wemodelthetrade-
B
off hypothesis as constrained cladogenetic diffusion.
First,aspeciesofmassM producesdescendantspecies
with masses λM (Fig. 2b), where λ is a randomvariable
representing short-term selective effects on size [29, 43]. M
With each λ drawn independently, short-term selections
on body sizes are uncorrelated across the clade and the me
clade’s size distribution evolves according to a diffusion ti
λM
process. The trajectory of any particular lineage fol-
lows a kind of random walk. When the average size
change between ancestors and descendants within a lin-
eage is biased toward larger sizes (Cope’s rule), we have
hlnλi > 0 [2]. (Size variation between speciation events
need not be modeled separately because its impact may
be absorbed into λ.) FIG. 2: (A) The characteristic distribution of species body
Second, species may not take any size and thus the sizes, observed in most major animal groups. Macroevo-
diffusion process is constrained. On the upper end, the lutionary tradeoffs between short-term selective advantages
probabilityofspeciesextinctionrisesgentlywithincreas- and long-term extinction risks, constrained by a minimum
ing size [25], e.g., due to larger energetic requirements, viable size Mmin, produce the distribution’s long right-tail.
smallerspeciesabundanceandlongergenerationaltimes. (B)Schematicillustratingthecladogeneticdiffusionmodelof
species body-sizeevolution: adescendant species’ mass isre-
The net effect is a soft upper limit. Given a particular
latedtoitsancestor’ssizeM byarandommultiplicativefac-
extinction risk curve, the number and size of very large
tor λ. Species become extinct with a probability that grows
speciesisdeterminedbythetotalnumberofspeciesinthe
slowly with M.
clade,which sets the rateatwhich smaller-sizedlineages
migrate into the larger and more risky size ranges [48].
Onthe lowerend,endothermyimposesaminimum vi-
coefficient or the variance in size change, and k −A is
able mass—a hard lower limit—that prohibits evolution
the size-independent (background) net speciation rate,
toward ever smaller sizes. For terrestrial mammals and
which sets the absolute scale of the mass frequencies.
birds, this thermoregulatory minimum size is known to
The aforementioned size constraints ensure conver-
occur atM =2g [33,50], below whicha species’con-
min gence on a steady state distribution. To solve for its
vectiveheatlossinairistoohightomaintainitsinternal
shape, we change variables µ = v/D, α = (k −A)/D,
temperature.
and β = B/D, and require that the distribution go to
To extract precise predictions for the distribution of
zero at x=x . It can then be shown that the steady-
min
species sizes, we formalize this model mathematically.
state distribution of sizes x is
Following Clauset and Redner [11], c(x,t) denotes the
density (fraction) of species having mass x = lnM at c(x)∝eµx/2Ai β1/3(x−x )+z , (2)
h min 0i
time t. Under mild assumptions, the value c(x,t) obeys
the convection-diffusion-reaction equation in the contin-
where Ai[.] is the Airy function and z = −2.3381... is
0
uum limit:
the location of its first zero [11, 12].
∂c ∂c ∂2c Inthis way,the predictedshapeofthespeciessize dis-
+v =D +(k−A−Bx)c , (1) tributionis fully determined by three model parameters:
∂t ∂x ∂x2
µ, the normalized strength of Cope’s rule, β, the nor-
wherev =hlnλiisthebiasoraveragechangeinsizefrom malizedsize-dependenceofextinctionrisk,andx ,the
min
ancestor to descendent, D = h(lnλ)2i is the diffusion logarithm of the minimum viable body size.
3
Estimates for µ and β for terrestrial mammals have
100
previouslybeenderivedfromfossilandextantdata. The A 77 cetacean species
resulting size distribution accurately reproduces both Predicted distribution
the extant sizes of terrestrial mammals [10] and their M
expansion during the late Cretaceous and early Paleo- ≥s
s
gene [11, 51]. Removing either the size-dependence of a
erexatliinsctticiopnreridsikctoiorntshe[1m0].inimum viable size produces un- with m10−1 sity ) B
n en
However, pelagic environments impose distinct phys- o D
iological, ecological and evolutionary challenges for en- acti og(
Fr l
dothermic mammals, which are not reflected in the ter-
restrial model. One critical difference is the greater con- 10−2 104 105 106 107 108 109
vectiveheatlossinwater,whichraisestheminimumsize
104 105 106 107 108
of a competent aquatic endotherm. Thermoregulatory
Species body mass (grams)
calculations and empirical data both estimate roughly
M =7kg for extant cetaceans [15], about 3500 times
min FIG.3: (A)Exante predictedcetaceansizes,fromacladoge-
larger than the minimum size in air.
netic model fitted to terrestrial mammals but with a pelagic
Mmin (see text), and empirical sizes of 77 extant cetacean
species, as complementary cumulative distributions and as
II. TESTS OF THE MODEL PREDICTIONS (B) smoothed probability densities.
To test the tradeoff hypothesis for cetaceans, we use
the terrestrial mammal model, but we shift M to its
min
pelagic value. That is, we use a model that successfully
ues. This yields a slightly lower but still non-significant
explains the sizes of terrestrial mammal species but we
p = 0.07±0.03, which does not alter our conclusion.
change the environmental constraint imposed by M ks
min
Thus, the macroevolutionary tradeoff fully explains the
so that the tradeoff unfolds in a pelagic environment.
observed sizes of cetacean species as a group.
This produces an ex ante prediction Pr(M) for extant
cetacean species sizes. Notably, the prediction has no
As an additional test, we consider whether the size of
tunable parameters by which to improve its agreement
the largest cetacean species would be considered a sta-
with observed sizes. This property makes its accuracy a
tistical outlier. The probability of observing at least one
strong test of the tradeoff’s universality.
species with size at least as large as the Blue Whale at
Previous analyses of terrestrial mammal data yielded
µˆ ≈ 0.2, a slight tendency toward larger sizes within a M∗ =1.75×108gwascomputedasp(M∗)=1−F(M∗)n
lineage (Cope’s rule), and βˆ≈0.08,a weak tendency for whereF(M∗)= M∗ Pr(M)M. is the portionofthe pre-
RMmin
extinction to increase with body size [11, 12]. dicted distribution below M∗ and n is the number of iid
To test the model’s accuracy, we constructed a novel observations (extant species) drawn from Pr(M). Tak-
bodysizedatasetforall77extantcetaceanspecies,from ing fixed parameters yields p = 0.91; simulating sta-
183empiricalsizeestimates[5,6,9,13,14,16–23,27,30– tistical uncertainty via Monte Carlo (as above) yields
32, 34–38, 40–42, 45–47, 49]. Only plausibly indepen- p = 0.88 ± 0.03, which is consistent with the fixed-
dent,scientificallyderivedestimateswereincluded. Mass parameter result.
ranges were convertedto point estimates by taking their
midpoint, unlessameanvalue wasalsoprovided. Subse- Thus, the enormous size of the Blue Whale is not a
quently,the meanvalue ofallpointestimates foragiven statistical outlier relative to the predicted distribution,
species wasused; this yielded anaverageof 2.4 measure- implying that the tradeoff mechanism alone is sufficient
ments per species. Tables I and II give the mass esti- explanation of the Blue Whale’s size. We note, how-
mates, primary source(s) and data curation comments. ever,thataspeciessomewhatlargerthantheBlueWhale
Figure 3 compares the predicted and empirical distri- wouldalsonotbe statisticallyunlikely, althoughno such
butions. We determinedthe prediction’sstatisticalplau- species is known to have existed.
sibilityrelativetothe empiricalsizesviaastandardtwo-
tailed Kolmogorov-Smirnov test, evaluated numerically. Finally, the value of β used here was estimated by
The resultant value p = 0.16±0.01 exceeds all con- fitting the model to extant terrestrial mammal data.
ks
ventionalthresholds for rejecting the nullhypothesis,in- Estimating β directly from the extant cetacean species
dicating that extant cetacean sizes are statistically in- size distribution only improves the fit of the model and
distinguishable from the predicted distribution. To sim- thus cannot change our conclusions. Doing so yields
ulate statistical uncertainty in µ and β, we estimated βˆ ≈ 0.097, which is close to the terrestrial mammals
cete
p via Monte Carlo by adding a small amount of Nor- value and supports our universality claim for the under-
ks
mally distributed noise to the terrestrial parameter val- lying processes shaping mammal evolution.
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III. DISCUSSION suggests that the energetically optimal body size expla-
nation of the species size distribution is flawed. This,
The accuracy of the model’s ex ante prediction con- in turn, suggests that the empirically observed pattern
firms that terrestrial and aquatic mammal sizes are of size changes among insular species [26, 39], and their
shaped by a single macroevolutionary tradeoff between hypothesized explanation [8], should be revisited.
short-term advantages—better resource fluctuation tol- The short-term-long-term tradeoff dynamic described
erance, thermoregulation and predator avoidance [7]— here is a neutral mechanism for species size evolution
and long-term extinction risks—largerenergetic require- within a clade, as it omits explicit mechanisms for eco-
ments, smaller species abundance and longer genera- logicallyimportant processes like species interaction,ge-
tionaltimes—of increasedsize, constrainedby endother- ography, climate, etc. Deviations from the predictions,
mic requirements at the lower end. Thus, cetaceans ex- like the slight over-abundance of cetaceans near 800kg
hibitlargebodysizesbecausegreaterconvectiveheatloss andunder-abundance near 100,000kg(Fig. 3a), may in-
in waterraisesthe minimum viablesize, whichshifts the dicate previously unrecognized non-neutral evolutionary
canonicaldistributionupwardandpushesitstailintosize orecologicalprocesses. Similarly,totheextentthatthey
ranges inaccessible to terrestrial mammals. canbe measuredinempiricaldata,changesinmodelpa-
This large minimum size was a significant barrier for rameter values over time may indicate broad-scale, non-
early terrestrial mammals, preventing their invasion of stationaryprocesseslikeclimatechange,e.g.,inthevalue
pelagic niches prior to roughly 60 Ma. Before this time, on xmin or the magnitude of µ, or clade-level ecological
there were few or no mammal species with sufficiently competition, as between mammals and dinosaurs prior
large masses [28], and therefore no mammals capable of to the K-Pg event.
living as competent aquatic endotherms. Only after the Finally, our assumptions of size-related macroevolu-
terrestrialmammalsizedistributionexpandedinthelate tionary tradeoffs are entirely general, but it remains un-
CretaceousandearlyPaleogene[11,51]wassuchatran- known whether they hold for other major clades, in-
sition possible, and mammals successfully invaded the cluding aquatic tetrapod groups like icthyosaurs, ple-
oceans almost immediately after these conditions were siosaurs and turtles, or dinosaurs, fish and foraminifera,
met. or whether it holds for other small taxonomic groups.
The general pattern of extant cetacean body sizes is A broad examination of minimum viable sizes and size-
compactly explained by only the normalized strength of dependent extinction risks acrossgroups and across geo-
Cope’s rule µ and the normalized size-dependence of ex- logic time may better elucidate the roleof species size in
tinctionrisksβ, whichtakeuniversalvalues forallmam- major evolutionary transitions and ecologicaltheory.
mals, terrestrial and aquatic. Given the first archaeo-
cete’s size, species counts over geological time and the
model diffusion rate, the model would predict when a Acknowledgments
species of a given size should first have appeared.
The success of the constrained cladogenetic diffusion The author thanks Doug Erwin and Sid Redner for
modelandthe tradeoffhypothesis inpredicting,without helpful conversations. This work was supported in part
tunable parameters,the sizes ofextantcetaceansfurther by the Santa Fe Institute.
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group family species mass(kg) primarysource(reference) curationcomments
Mysticeti Balaenidae Balaenamysticetus 100000 Smithetal(2003) .
Mysticeti Balaenidae Balaenamysticetus 87500 JeffersonLeatherwoodWebber(1993) .
Mysticeti Balaenidae Eubalaenaaustralis 23000 Smithetal(2003) .
Mysticeti Balaenidae Eubalaenaaustralis 100000 JeffersonLeatherwoodWebber(1993) .
Mysticeti Balaenidae Eubalaenaglacialis 23000 Smithetal(2003) .
Mysticeti Balaenidae Eubalaenaglacialis 90000 JeffersonLeatherwoodWebber(1993) .
Mysticeti Balaenopteridae Balaenopteraacutorostrata 10000 Smithetal(2003) .
Mysticeti Balaenopteridae Balaenopteraacutorostrata 14000 JeffersonLeatherwoodWebber(1993), .
PerrinZubtsovaKuzmin(2004)
Mysticeti Balaenopteridae Balaenopteraborealis 20000 Smithetal(2003) .
Mysticeti Balaenopteridae Balaenopteraborealis 30000 JeffersonLeatherwoodWebber(1993), .
Long1968
Mysticeti Balaenopteridae Balaenopteraedeni 20000 Smithetal(2003) .
Mysticeti Balaenopteridae Balaenopteraedeni 22500 JeffersonLeatherwoodWebber(1993) .
Mysticeti Balaenopteridae Balaenopteramusculus 190000 Smithetal(2003) .
Mysticeti Balaenopteridae Balaenopteramusculus 160000 JeffersonLeatherwoodWebber(1993), .
Mortoned1997
Mysticeti Balaenopteridae Balaenopteraphysalus 70000 Smithetal(2003) .
Mysticeti Balaenopteridae Balaenopteraphysalus 75000 Jefferson Leatherwood Webber .
(1993), Uhen Fordyce Barnes 1998
inJanisGunnellUhen
Mysticeti Balaenopteridae Megapteranovaeangliae 30000 Smithetal(2003) .
Mysticeti Balaenopteridae Megapteranovaeangliae 35000 JeffersonLeatherwoodWebber(1993), .
Clapham Mead 1999, Uhen Fordyce
Barnes1998inJanisGunnellUhen
Mysticeti Eschrichtiidae Eschrichtiusrobustus 28500 Smithetal(2003) .
Mysticeti Eschrichtiidae Eschrichtiusrobustus 35000 Jefferson Leatherwood Webber .
(1993), Uhen Fordyce Barnes 1998
inJanisGunnellUhen
Mysticeti Neobalaenidae Capereamarginata 3200 JeffersonLeatherwoodWebber(1993), estimate by Smith etal 2003 gives a mass 10x as
PerrinZubtsovaKuzmin(2004) large,soweomitSmithetal
Odontoceti Delphinidae Cephalorhynchuscommersonii 72.4 Smithetal(2003) .
Odontoceti Delphinidae Cephalorhynchuscommersonii 76 JeffersonLeatherwoodWebber(1993) .
Odontoceti Delphinidae Cephalorhynchuscommersonii 86 Culik(2004) .
Odontoceti Delphinidae Cephalorhynchuseutropia 45 Smithetal(2003) .
Odontoceti Delphinidae Cephalorhynchuseutropia 63 JeffersonLeatherwoodWebber(1993) .
Odontoceti Delphinidae Cephalorhynchuseutropia 60 Culik(2004) .
Odontoceti Delphinidae Cephalorhynchusheavisidii 40 Smithetal(2003) .
Odontoceti Delphinidae Cephalorhynchusheavisidii 65 Culik(2004) .
Odontoceti Delphinidae Cephalorhynchushectori 50 Smithetal(2003) .
Odontoceti Delphinidae Cephalorhynchushectori 57 JeffersonLeatherwoodWebber(1993) .
Odontoceti Delphinidae Delphinusdelphis 80 Smithetal(2003) .
Odontoceti Delphinidae Delphinusdelphis 135 JeffersonLeatherwoodWebber(1993) .
Odontoceti Delphinidae Delphinusdelphis 200 Culik(2004) .
Odontoceti Delphinidae Feresaattenuata 170 Smithetal(2003) .
Odontoceti Delphinidae Feresaattenuata 225 JeffersonLeatherwoodWebber(1993) .
Odontoceti Delphinidae Globicephalamacrorhynchus 726 Smithetal(2003) .
Odontoceti Delphinidae Globicephalamacrorhynchus 3600 JeffersonLeatherwoodWebber(1993) .
Odontoceti Delphinidae Globicephalamelas 800 Smithetal(2003) .
Odontoceti Delphinidae Globicephalamelas 2000 JeffersonLeatherwoodWebber(1993) .
Odontoceti Delphinidae Globicephalamelas 1600 PerrinZubtsovaKuzmin(2004) .
Odontoceti Delphinidae Grampusgriseus 387.5 Smithetal(2003) .
Odontoceti Delphinidae Grampusgriseus 400 JeffersonLeatherwoodWebber(1993) .
Odontoceti Delphinidae Lagenodelphishosei 164 Smithetal(2003) .
Odontoceti Delphinidae Lagenodelphishosei 210 JeffersonLeatherwoodWebber(1993) .
Odontoceti Delphinidae Lagenodelphishosei 210 Culik(2004) .
Odontoceti Delphinidae Lagenodelphishosei 209 JeffersonLeatherwood1994 .
Odontoceti Delphinidae Lagenorhynchusacutus 182 Smithetal(2003) .
Odontoceti Delphinidae Lagenorhynchusacutus 208.5 JeffersonLeatherwoodWebber(1993) .
Odontoceti Delphinidae Lagenorhynchusacutus 205 Culik(2004) .
Odontoceti Delphinidae Lagenorhynchusalbirostris 180 Smithetal(2003) .
Odontoceti Delphinidae Lagenorhynchusalbirostris 265 Culik(2004) .
Odontoceti Delphinidae Lagenorhynchusaustralis 120 Smithetal(2003) .
Odontoceti Delphinidae Lagenorhynchusaustralis 115 JeffersonLeatherwoodWebber(1993) .
Odontoceti Delphinidae Lagenorhynchusaustralis 115 Culik(2004) .
Odontoceti Delphinidae Lagenorhynchuscruciger 110 Smithetal(2003) .
Odontoceti Delphinidae Lagenorhynchusobliquidens 120 Smithetal(2003) .
Odontoceti Delphinidae Lagenorhynchusobliquidens 180 JeffersonLeatherwoodWebber(1993) .
Odontoceti Delphinidae Lagenorhynchusobliquidens 82.5 Culik(2004) .
Odontoceti Delphinidae Lagenorhynchusobscurus 127.5 Smithetal(2003) .
Odontoceti Delphinidae Lagenorhynchusobscurus 60 JeffersonLeatherwoodWebber(1993) .
Odontoceti Delphinidae Lagenorhynchusobscurus 100 Culik(2004) .
Odontoceti Delphinidae Lissodelphisborealis 113 Smithetal(2003) .
Odontoceti Delphinidae Lissodelphisborealis 115 JeffersonLeatherwoodWebber(1993) .
Odontoceti Delphinidae Lissodelphisborealis 116 Culik(2004) .
Odontoceti Delphinidae Lissodelphisborealis 113 JeffersonNewcomer(1993) .
Odontoceti Delphinidae Lissodelphisperonii 116 Smithetal(2003) .
Odontoceti Delphinidae Lissodelphisperonii 116 JeffersonLeatherwoodWebber(1993) Culik 2004 repeats this measurement, so we omit
Culik
Odontoceti Delphinidae Lissodelphisperonii 116 NewcomerJeffersonBrownell1996 .
Odontoceti Delphinidae Orcaellabrevirostris 190 Smithetal(2003) .
Odontoceti Delphinidae Orcaellabrevirostris 122.5 Culik(2004) .
Odontoceti Delphinidae Orcaellabrevirostris 123.5 StaceyArnold1999 .
Odontoceti Delphinidae Orcinusorca 4300 Smithetal(2003) .
Odontoceti Delphinidae Orcinusorca 8750 JeffersonLeatherwoodWebber(1993) .
Odontoceti Delphinidae Orcinusorca 4685 Culik(2004) .
Odontoceti Delphinidae Orcinusorca 7050 PerrinZubtsovaKuzmin(2004) reportedmassmeanof2specimens
Odontoceti Delphinidae Peponocephalaelectra 208 Smithetal(2003) .
Odontoceti Delphinidae Peponocephalaelectra 275 JeffersonLeatherwoodWebber(1993) .
Odontoceti Delphinidae Peponocephalaelectra 228 Culik(2004) .
Odontoceti Delphinidae Peponocephalaelectra 208 JeffersonBarros1997 .
Odontoceti Delphinidae Pseudorcacrassidens 1360 Smithetal(2003) .
Odontoceti Delphinidae Pseudorcacrassidens 2000 JeffersonLeatherwoodWebber(1993) .
Odontoceti Delphinidae Pseudorcacrassidens 1360 StaceyLeatherwood1994 .
Odontoceti Delphinidae Sotaliafluviatilis 44 Smithetal(2003) .
Odontoceti Delphinidae Sotaliafluviatilis 40 JeffersonLeatherwoodWebber(1993) .
Odontoceti Delphinidae Sousachinensis 265 Smithetal(2003) .
Odontoceti Delphinidae Sousachinensis 284 JeffersonLeatherwoodWebber(1993) .
Odontoceti Delphinidae Sousachinensis 215 Culik(2004) .
Odontoceti Delphinidae Sousachinensis 265 JeffersonKarczmarksi(2001) .
Odontoceti Delphinidae Sousateuszii 100 Smithetal(2003) .
Odontoceti Delphinidae Sousateuszii 284 JeffersonLeatherwoodWebber(1993) .
Odontoceti Delphinidae Sousateuszii 215 Culik(2004) .
Odontoceti Delphinidae Sousateuszii 166 Waerebeeketal(2004) .
TABLE I: Cetacean size estimates (part 1).
7
group family species mass(kg) primarysource(reference) curationcomments
Odontoceti Delphinidae Stenellaattenuata 120 JeffersonLeatherwoodWebber(1993) estimatefromSmithetal2003islessthan1/2ofthe
valuesreportedelsewhere,soweomitSmithetal
Odontoceti Delphinidae Stenellaattenuata 119 Culik(2004) .
Odontoceti Delphinidae Stenellaattenuata 119 Perrin(2001) .
Odontoceti Delphinidae Stenellaclymene 68 Smithetal(2003) .
Odontoceti Delphinidae Stenellaclymene 85 JeffersonLeatherwoodWebber(1993) .
Odontoceti Delphinidae Stenellaclymene 80 Culik(2004) .
Odontoceti Delphinidae Stenellaclymene 80 JeffersonCurry(2003) .
Odontoceti Delphinidae Stenellacoeruleoalba 135.9 Smithetal(2003) .
Odontoceti Delphinidae Stenellacoeruleoalba 156 JeffersonLeatherwoodWebber(1993) .
Odontoceti Delphinidae Stenellacoeruleoalba 156 Culik(2004) .
Odontoceti Delphinidae Stenellafrontalis 110 Smithetal(2003) .
Odontoceti Delphinidae Stenellafrontalis 143 JeffersonLeatherwoodWebber(1993) .
Odontoceti Delphinidae Stenellafrontalis 143 Culik(2004) .
Odontoceti Delphinidae Stenellafrontalis 140 Perrin(2002) .
Odontoceti Delphinidae Stenellalongirostris 50.5 Smithetal(2003) .
Odontoceti Delphinidae Stenellalongirostris 77 JeffersonLeatherwoodWebber(1993) .
Odontoceti Delphinidae Stenellalongirostris 50.5 Perrin1998 Culik2004repeats measurementofPerrin1998, so
weomitCulik
Odontoceti Delphinidae Stenobredanensis 130 Smithetal(2003) .
Odontoceti Delphinidae Stenobredanensis 150 JeffersonLeatherwoodWebber(1993) .
Odontoceti Delphinidae Stenobredanensis 155 Culik(2004) .
Odontoceti Delphinidae Tursiopstruncatus 175 Smithetal(2003) .
Odontoceti Delphinidae Tursiopstruncatus 650 JeffersonLeatherwoodWebber(1993) .
Odontoceti Delphinidae Tursiopstruncatus 242 Culik(2004) .
Odontoceti Monodontidae Delphinapterusleucas 1360 Smithetal(2003) .
Odontoceti Monodontidae Delphinapterusleucas 1500 Steward Steward (1989), .
Uhen Fordyce Barnes 1998
inJanisGunnellUhen
Odontoceti Monodontidae Delphinapterusleucas 1500 Culik(2004) .
Odontoceti Monodontidae Delphinapterusleucas 1600 JeffersonLeatherwoodWebber(1993) .
Odontoceti Monodontidae Monodonmonoceros 900 Smithetal(2003) .
Odontoceti Monodontidae Monodonmonoceros 1600 JeffersonLeatherwoodWebber(1993), .
ReevesTracey(1980)
Odontoceti Monodontidae Monodonmonoceros 1300 Culik(2004) .
Odontoceti Phocoenidae Australophocaenadioptrica 65 Smithetal(2003) .
Odontoceti Phocoenidae Neophocaenaphocaenoides 32.5 Smithetal(2003) .
Odontoceti Phocoenidae Neophocaenaphocaenoides 85 Culik(2004) .
Odontoceti Phocoenidae Neophocaenaphocaenoides 71.8 JeffersonHung(2004) .
Odontoceti Phocoenidae Phocoenaphocoena 52.5 Smithetal(2003) .
Odontoceti Phocoenidae Phocoenaphocoena 57.5 JeffersonLeatherwoodWebber(1993) .
Odontoceti Phocoenidae Phocoenaphocoena 55 Culik(2004) .
Odontoceti Phocoenidae Phocoenasinus 42.5 Smithetal(2003) .
Odontoceti Phocoenidae Phocoenaspinipinnis 60 Smithetal(2003) .
Odontoceti Phocoenidae Phocoenaspinipinnis 85 JeffersonLeatherwoodWebber(1993) .
Odontoceti Phocoenidae Phocoenoidesdalli 102.5 Smithetal(2003) .
Odontoceti Phocoenidae Phocoenoidesdalli 200 JeffersonLeatherwoodWebber(1993) .
Odontoceti Phocoenidae Phocoenoidesdalli 200 Culik(2004) .
Odontoceti Phocoenidae Phocoenoidesdalli 200 Jefferson(1988) .
Odontoceti Physeteridae Kogiabreviceps 431.5 Culik (2004), Borsa (2006), .
Uhen Fordyce Barnes (1998)
inJanisGunnellUhen
Odontoceti Physeteridae Kogiabreviceps 450 Culik(2004) .
Odontoceti Physeteridae Kogiabreviceps 400 Borsa (2006), Jefferson Leatherwood .
Webber(1993), UhenFordyceBarnes
(1998)inJanisGunnellUhen
Odontoceti Physeteridae Kogiasimus 183.1 Smithetal(2003) .
Odontoceti Physeteridae Kogiasimus 270 Nagorsen1985 .
Odontoceti Physeteridae Kogiasimus 270 Culik(2004) mass quoted as 2702 kg, but this is too bigby an
orderofmagnitude. Assumedtobe270.2kg
Odontoceti Physeteridae Kogiasimus 210 JeffersonLeatherwoodWebber(1993) .
Odontoceti Physeteridae Physetercatodon 14025 Smithetal(2003) .
Odontoceti Physeteridae Physetercatodon 57000 JeffersonLeatherwoodWebber(1993), .
Cranford(1999)
Odontoceti Platanistidae Iniageoffrensis 129.25 Smithetal(2003) .
Odontoceti Platanistidae Iniageoffrensis 160 JeffersonLeatherwoodWebber(1993) .
Odontoceti Platanistidae Iniageoffrensis 167.5 Culik(2004) .
Odontoceti Platanistidae Iniageoffrensis 129.25 BestSilva(1993) .
Odontoceti Platanistidae Lipotesvexillifer 187.5 JeffersonLeatherwoodWebber(1993) massestimatefromSmithetal2003islessthan1/2
estimatedrangehere,soweomitSmithetal
Odontoceti Platanistidae Platanistagangetica 115 Smithetal(2003) .
Odontoceti Platanistidae Platanistagangetica 108 JeffersonLeatherwoodWebber(1993) .
Odontoceti Platanistidae Platanistaminor 83.9146 Smithetal(2003) .
Odontoceti Platanistidae Pontoporiablainvillei 40.5 Smithetal(2003) .
Odontoceti Platanistidae Pontoporiablainvillei 34 JeffersonLeatherwoodWebber(1993) .
Odontoceti Ziphiidae Berardiusarnuxii 7000 Smithetal(2003) .
Odontoceti Ziphiidae Berardiusbairdii 11380 Smithetal(2003) .
Odontoceti Ziphiidae Berardiusbairdii 12000 JeffersonLeatherwoodWebber(1993) .
Odontoceti Ziphiidae Hyperoodonampullatus 5800 Smithetal(2003) .
Odontoceti Ziphiidae Hyperoodonplanifrons 3000 Smithetal(2003) .
Odontoceti Ziphiidae Indopacetuspacificus 2200 Smithetal(2003) .
Odontoceti Ziphiidae Mesoplodonbidens 3400 Smithetal(2003) .
Odontoceti Ziphiidae Mesoplodonbowdoini 2600 Smithetal(2003) .
Odontoceti Ziphiidae Mesoplodoncarlhubbsi 1400 JeffersonLeatherwoodWebber(1993) .
Odontoceti Ziphiidae Mesoplodoncarlhubbsi 3400 Smithetal(2003) .
Odontoceti Ziphiidae Mesoplodoncarlhubbsi 500 MeanWalkerHouck1982 .
Odontoceti Ziphiidae Mesoplodondensirostris 2300 Smithetal(2003) .
Odontoceti Ziphiidae Mesoplodondensirostris 1033 JeffersonLeatherwoodWebber(1993) .
Odontoceti Ziphiidae Mesoplodoneuropaeus 5600 Smithetal(2003) .
Odontoceti Ziphiidae Mesoplodoneuropaeus 1200 JeffersonLeatherwoodWebber(1993) .
Odontoceti Ziphiidae Mesoplodonginkgodens 1500 Smithetal(2003) .
Odontoceti Ziphiidae Mesoplodongrayi 2900 Smithetal(2003) .
Odontoceti Ziphiidae Mesoplodongrayi 1100 JeffersonLeatherwoodWebber(1993) .
Odontoceti Ziphiidae Mesoplodonhectori 1000 Smithetal(2003) .
Odontoceti Ziphiidae Mesoplodonlayardii 1500 Smithetal(2003) .
Odontoceti Ziphiidae Mesoplodonmirus 2100 Smithetal(2003) .
Odontoceti Ziphiidae Mesoplodonmirus 1400 JeffersonLeatherwoodWebber(1993) .
Odontoceti Ziphiidae Mesoplodonmirus 1400 Culik(2004) .
Odontoceti Ziphiidae Mesoplodonstejnegeri 4800 Smithetal(2003) .
Odontoceti Ziphiidae Tasmacetusshepherdi 2500 Smithetal(2003) .
Odontoceti Ziphiidae Ziphiuscavirostris 4775 Smithetal(2003) .
Odontoceti Ziphiidae Ziphiuscavirostris 3000 JeffersonLeatherwoodWebber(1993) .
TABLE II: Cetacean size estimates (part 2).