Answers Research Journal 8 (2015):85–91. www.answersingenesis.org/arj/v8/average-dinosaur-size.pdf Determining Average Dinosaur Size Using the Most Recent Comprehensive Body Mass Data Set
Timothy L. Clarey, Institute for Creation Research, 1806 Royal Lane, Dallas, Texas 75229. Jeffrey P. Tomkins, Institute for Creation Research, 1806 Royal Lane, Dallas, Texas 75229. Abstract The median mass of a dinosaur is determined to be 630 kg (1389 lb), or the size of an American bison, based on the largest published and most accurate data set to date. Most dinosaurs seem to have stayed very small (0–60 kg [0–132 lb]) or grew very large (1081–56,000 kg [2383–123,459 lb]), with less species in the medium-sized range. The dinosaurs buried in the lower Flood layers (Upper Triassic series) were mostly small. Although there was an average size increase upward into younger Flood layers, it was not universal or statistically strong. There were many small dinosaurs buried throughout the entire spectrum of dinosaur-bearing rocks. The largest sauropodomorphs were buried in the Upper Jurassic series, about midway through the Flood record of dinosaurs. Whereas, ornithopods showed an increase in size from earliest to latest Flood deposits, attaining greatest size in the Upper Cretaceous series. Theropods generally showed an increase in size from the earliest deposits to the later Flood deposits, but had a small peak in size in the Middle Jurassic deposits also. The sizes of dinosaurs buried at different times LQWKH)ORRGVHHPWRKDYHEHHQLQÁXHQFHGE\VHYHUDOIDFWRUVLQFOXGLQJKDELWDWHOHYDWLRQPRELOLW\DQG reaction to danger or intelligence. The larger brain size and mobility of the coelurosaur theropods may explain their prevalence in the Cretaceous system. Higher mobility of theropods in general may explain their greater than expected proportion of footprints also.
Keywords: dinosaur mass, dinosaur size, Sauropodomorph, Theropod, Marginocephalia, Ornithopod, Thyreophoran, Ornithischia
Introduction Herrerasauria It has often been stated in the literature that the average dinosaur was only the size of a sheep or large Ceratosauria dog. This notion probably originated in the secular Carnosauria VFLHQWLÀFOLWHUDWXUHZKHUH+RUQHUDQG/HVVHP have claimed that most dinosaurs were smaller Coelurosauria than bulls, and in popular literature where Crichton Theropoda
KDVVWDWHGWKDWWKH\ZHUHWKHVL]HRIVKHHSRU Saurischia Therizinosauridae a pony. Unfortunately, most of these estimates have been based on very little empirical data. It is critical Sauropoda that creationists base their statements on the best available data, so this contribution hopefully assists that endeavor. Prosauropoda There are about 1350 species of dinosaurs, with Sauropodomorpha
VHYHUDOQHZQDPHGHDFK\HDU 2·*RUPDQDQG+RQH Dinosauria Fabrosauridae 0RVW RI WKHVH DUH QDPHG RQ LQFRPSOHWH specimens, so occasionally a species becomes Ornithopods combined with another, reducing the overall number Ornithopoda RIVSHFLHV%HQWRQ HVWLPDWHGWKDWWKHRYHUDOO Pachycephalosauria success rate in naming a new dinosaur species has been about 50%. A lot of this uncertainty is due to the
Ornithischia Ceratopsia fragmentary nature of most discoveries. Fig. 1 shows one way to classify dinosaurs. Marginocephalia Stegosauria 'LQRVDXULDDUHÀUVWGLYLGHGLQWRWZRFODGHV 2UGHUV
E\KLSVW\OHWKH2UQLWKLVFKLD ELUGKLSSHG DQGWKH Ankylosauria
6DXULVFKLD OL]DUGKLSSHG 7KHVH WZR JURXSV DUH Thyreophora IXUWKHU VXEGLYLGHG LQWR ÀYH VXERUGHUV EDVHG RQ Fig. 1. &XUUHQW VHFXODU FODVVLÀFDWLRQ KLHUDUFK\ IRU DGGLWLRQDO VNHOHWDO VLPLODULWLHV WKH 7K\UHRSKRUD dinosaurs.
ISSN: 1937-9056 Copyright © 2015, 2016 Answers in Genesis, Inc. All content is owned by Answers in Genesis (“AiG”) unless otherwise indicated. AiG consents to unlimited copying and distribution of print copies of Answers Research Journal articles for non-commercial, non-sale purposes only, provided the following conditions are met: the author of the article is clearly identified; Answers in Genesis is acknowledged as the copyright owner; Answers Research Journal and its website, www.answersresearchjournal.org, are acknowledged as the publication source; and the integrity of the work is not compromised in any way. For website and other electronic distribution and publication, AiG consents to republication of article abstracts with direct links to the full papers on the ARJ website. All rights reserved. For more information write to: Answers in Genesis, PO Box 510, Hebron, KY 41048, Attn: Editor, Answers Research Journal.
The views expressed are those of the writer(s) and not necessarily those of the Answers Research Journal Editor or of Answers in Genesis. 86 T. L. Clarey and J. P. Tomkins
WKH 0DUJLQRFHSKDOLD WKH 2UQLWKRSRGD WKH ERQHV DQ DYHUDJH GLQRVDXU VL]H KDV EHHQ GLIÀFXOW Sauropodomorpha and the Theropoda. Currently WR GHWHUPLQH $Q HDUO\ DWWHPSW E\ 3HF]NLV accepted infraorders are also shown for each XVHGGLQRVDXUJHQHUD3HF]NLVGHWHUPLQHGWKDW suborder. The data set used in this study occasionally the mass of dinosaurs varied across six orders of differentiated down to the Family level. magnitude with the modal mass range falling in Determining the exact mass of a dinosaur is WKH ²WRQQHV ² 86 VKRUW WRQV ² VRPHWKLQJZH·OOQHYHUEHDEOHWRGRZLWKRXWDOLYLQJ %ULWLVK ORQJ WRQV FDWHJRU\ 0RUH UHFHQW UHVHDUFK VSHFLPHQ6FLHQWLVWVFDQRQO\PDNHHVWLPDWHVXVLQJ has examined individual species instead of genera. VNHOHWDO GDWD )RU WKLV UHDVRQ PDVV HVWLPDWHV 2·*RUPDQ DQG +RQH XVHG VSHFLHV RI for some dinosaurs have changed dramatically dinosaurs, but relied heavily on less accurate over the years. The earliest models and paintings methods of mass estimation, including bone lengths portrayed dinosaurs as fat, sluggish, lethargic- DQG VFDOH PRGHOV %HQVRQ HW DO H[FOXVLYHO\ ORRNLQJUHSWLOHV0RVWRIWKHÀUVWUHFRQVWUXFWLRQVRI used leg bone shaft circumference measurements of XSULJKWGLQRVDXUVZHUHLQWKHFODVVLFNDQJDURROLNH 441 species of dinosaurs and fossil birds to compile pose, with the tail dragging on the ground behind. their mass estimates. 0RUH UHFHQW SRUWUD\DOV KDYH PDGH GLQRVDXUV LQWR leaner and more agile-moving creatures. Detailed Methods FRPSXWHU DQDO\VHV IRRWSULQW GDWD VKRZLQJ D ODFN 7KH GDWD XVHG LQ WKLV VWXG\ ZDV WDNHQ IURP RIWDLOGUDJJLQJPDUNVDQGPRYLHVVXFKDVJurassic the species listed in Dataset S1 of Benson et al. Park have made these slimmer reconstructions 7KHVH GDWD LQFOXGH VSHFLHV QDPH VXERUGHU mainstream. FODVVLÀFDWLRQVRPHLQIUDRUGHUVDPDVVHVWLPDWH NJ There are three generally accepted ways if leg bone material was available and the level of WR HVWLPDWH GLQRVDXU PDVV XVH RI OHJ ERQH RFFXUUHQFHLQWKHURFNVWUDWD7KLVLVOLNHO\WKHPRVW FLUFXPIHUHQFHV XVH RI ÁHVKHGRXW VFDOH PRGHOV accurate, and comprehensive, data set of dinosaur DQG XVHRIOHJERQHOHQJWKV6RPHSDOHRQWRORJLVWV mass estimates to date. Unfortunately the data set SUHIHU WR XVH VFDOH PRGHOV /XFDV EXW WKHUH also included many fossil birds. are distinct advantages and disadvantages to all Before beginning our study, we eliminated all mass methods. The beauty of the circumference method is HVWLPDWHVWKDWZHUHFODVVLÀHGDVELUGV $YLDODH DQG in its simplicity. All a paleontologist needs is a couple ÀYHDUJXDEOHELUGOLNHVSHFLHVWKDWZHUHFODVVLÀHGDV of leg bones, which are often well preserved, in order theropods such as Microraptor gui. We also dropped WRPDNHDUHDVRQDEOHHVWLPDWHRIERG\PDVVDQGWKH all species that had no given mass estimate, paring same is true of the leg-length method. GRZQ RXU DQDO\VLV WR D ÀQDO WRWDO RI GLQRVDXU $QGHUVRQ +DOO0DUWLQ DQG 5XVVHOO VSHFLHV 7KLV ÀQDO GDWD VHW LQFOXGHG VRPH PDVV developed a method to estimate mass of a quadruped estimates from different species within the same based on the circumferences of the humerus and genus when leg bone material was available. We also femur bones, measured at the midpoint where left in 10 theropods and one sauropodomorph with the bones are the thinnest. They summed the two PXOWLSOH WZRDQGVRPHWLPHVWKUHH PDVVHVWLPDWHV circumferences and plotted the value against body from the same species, but determined using different mass on a logarithmic scale and found a straight- specimens. OLQHUHODWLRQVKLSDQGFRUUHVSRQGLQJEHVWÀWHTXDWLRQ :HZHUHDEOHWRH[WUDFWFODVVLÀFDWLRQLQIRUPDWLRQ for us to use. A similar method involving the from the published data set to place each of the circumference of only the femur was also developed GLQRVDXUVLQWRRQHRIWKHÀYHVXERUGHUVOLVWHGLQ)LJ IRU ELSHGDO GLQRVDXUV $QGHUVRQ +DOO0DUWLQ DQG )XUWKHU FODVVLÀFDWLRQ LQWR LQIUDRUGHUV ZDV QRW 5XVVHOO attempted as the numbers in some of these categories The scale model method requires a more complete ZHUH TXLWH VPDOO PDNLQJ VWDWLVWLFDO DQDO\VLV OHVV VNHOHWRQWREHJLQZLWKLQRUGHUWRPDNHDQHVWLPDWH meaningful. We also used the geologic occurrence and may be less accurate due to a possible greater information given for each specimen to place the YDULDWLRQ LQ WKH ÁHVKHGRXW YROXPH RI WKH PRGHO dinosaurs into one of six, accepted geologic series, %HQVRQ HW DO 7KH OHJ ERQH OHQJWK PHWKRG WKH8SSHU7ULDVVLFWKH/RZHU-XUDVVLFWKH0LGGOH of estimating dinosaur mass is also thought to be -XUDVVLFWKH8SSHU-XUDVVLFWKH/RZHU&UHWDFHRXV less reliable compared to the circumference method and the Upper Cretaceous, in ascending Flood %HQVRQHWDO depositional order. Two of the 350 dinosaur species There have been several large studies that have used in this study did not have any geologic series tried to address the question of average dinosaur information provided. Statistics and graphing of data size. However, because most dinosaur specimens are ZHUHGRQHXVLQJERWK06([FHODQGWKH5VWDWLVWLFDO LQFRPSOHWH DQG PDQ\ GR QRW SRVVHVV VXIÀFLHQW OHJ programming language. Determining Average Dinosaur Size Using the Most Recent Comprehensive Body Mass Data Set 87
Results >² OE@ RU YHU\ KHDY\ ² NJ >² Basic mass trends OE@ 7KHIHZHVWGLQRVDXUVLQWKHGDWDVHWIDOOLQWKH² Table 1 shows the overall basic statistics for NJ ² OE UDQJH 6R \HV WKHUH were a lot of small the dataset. Adult dinosaur masses were found to dinosaurs, but there were even more large and UDQJHIURPNJ OE WRNJ OE extremely large dinosaurs. For some reason though, the LQ WKLV GDWD VHW ZLWK D PHDQ RI NJ OE medium-sized dinosaur was the least common. This may DQG D PHGLDQ RI NJ OE 7KLV PHDQ LV have to do with the ecological QLFKHV WKDW VPDOO DQG ODUJH approximately equivalent to a small adult African GLQRVDXUVZHUHDEOHWRILOOor it could be a designed survival elephant and the median mass is equivalent to tactic. A really small dinosaur could hide PRUH easiO\ and an adult American bison. However, median size a large dinosaur was OHVV OLNHO\ WR EH WKUHDWHQHG E\ is probably a better measure of the average adult SUHGDWRUV ,W ZDV OLNHO\ an advantage to be one or the GLQRVDXU VL]H DV LW LV QRW VNHZHG DV PXFK E\ WKH other. On the other side, small predators could hunt high number of sauropodomorph specimens in small prey and large predators could hunt larger prey, the data base, and their extreme size, compared possibly explaining why there were fewer medium-sized to the mean. Table 1 also shows that there are predators also. VPDOO GLQRVDXUV OHVV WKDQ NJ >OE@ LQ HYHU\ 7KHVH GDWD VKRZ WKDW LW LV XQOLNHO\ WKDW WKH suborder of dinosaurs, except the Thyreophora. As average dinosaur was the size of a large dog or pony expected, the median and mean are highest for the as often quoted in the literature. Instead, a median- sauropodomorphs and smallest for the theropods. sized adult dinosaur was comparable to the mass Fig. 2 shows the number of dinosaurs in RIDPRGHUQDGXOWELVRQ+RZHYHUMXVWEHFDXVHWKH various mass categories in the data set. This median size of an adult dinosaur was fairly large, it graph suggests adult dinosaur masses exhibit a GRHVQ·W PHDQ WKHUH ZDV D URRP SUREOHP RQ 1RDK·V ELPRGDO GLVWULEXWLRQ HLWKHU YHU\ OLJKW ²NJ $UNGXULQJWKHJOREDO)ORRG¬0RVWGLQRVDXUSDLUVRQ WKH $UN ZRXOG OLNHO\ KDYH EHHQ MXYHQLOHV RU \RXQJ Table 1. %DVLF PDVV NJ VWDWLVWLFV IRU WKH ÀYH PDMRU adults, not the largest and oldest dinosaurs so often dinosaur orders. VHHQLQPXVHXPVSHFLPHQV7KHGLQRVDXUVWDNHQRQ N Range Mean Median WKH$UNPLJKWKDYHRQO\DYHUDJHG²NJ ² Sauropodomorphs 91 1.2 to 56,000 12,640 9800 OE RUDERXWVKHHSVL]HG Theropods 152 0.14 to 7700 652 99 All dinosaurs went through a year or two when Marginocephalia 25 3 to 14,000 2305 120 they grew very rapidly, a growth spurt similar to Thyreophora 18 610 to 7400 2858 2300 WHHQDJHKXPDQV (ULFNVRQ5RJHUVDQG 60 50 40 30 Number of species 20 10 0 0–5 6–20 21–60 61–120 121–360 361–1080 1081–3240 3241–9720 9721–56,000 Mass groupings (kg) Fig. 2. Numbers of dinosaur species by mass groupings. Each successive group in the series incrementally increase by ~3×. 88 T. L. Clarey and J. P. Tomkins the Flood and their release to land, the dinosaurs mean mass stays nearly constant through the last of would have experienced their growth spurt, rapidly the dinosaur-bearing stratum, the Upper Cretaceous maturing to adult size and sexual maturity, and VHULHV ZKHUH WKH PHDQ PDVV LV NJ OE WKHUHIRUHDEOHWRIXOÀOO*RG·VSODQWRUHSRSXODWHDQG These data suggest that dinosaur deposition as a ÀOOWKHHDUWK *HQHVLV whole did not get systematically larger and larger as the period of the deluge progressed. Results of dinosaur mass by order of Flood burial Although only small varieties of dinosaurs are We also examined the data set for mass found in the lowest dinosaur-bearing strata, similar distribution patterns with order of deposition in small dinosaurs are found continually throughout all the Flood sediments. It has been suggested that the subsequent Flood strata, through the Upper Cretaceous larger dinosaurs might have survived longer as they series. The mean mass in each higher level stratum is were more mobile and able to withstand the earlier merely altered by the immense sizes of dinosaurs found )ORRG HYHQWV FRPSDUHG WR VPDOOHU RQHV 6QHOOLQJ LQ-XUDVVLFDQG&UHWDFHRXVVWUDWD 7KLVLPSOLHVDUHODWLRQVKLSWRVL]HDQGWLPLQJ We also conducted linear regression analysis of burial in the Flood, and that dinosaurs should of the 348 dinosaur taxa to see if there was any become larger with time, sorting themselves upward statistical correlation between dinosaur mass and in the Flood strata. VWUDWD 7KH 5YDOXH ZDV QHDUO\ ]HUR DW ï In order to test this hypothesis, we analyzed the due to the inclusion of many small dinosaurs in WRWDOGLQRVDXU Q GLVWULEXWLRQE\VWUDWXPDQG HYHU\VWUDWXP )LJ 2YHUDOOLWFDQEHVDLGWKDW the individual suborders of the Sauropodomorphs, WKHUHLVQRVLJQLÀFDQWFRUUHODWLRQEHWZHHQGLQRVDXU Theropods, and Ornithopods by their order of mass and strata. However, a visual inspection of GHSRVLWLRQ:HGLGQRWH[DPLQHWKH0DUJLQRFHSKDOLD the plots indicated that the sauropodomorphs were Q DQG 7K\UHRSKRUD Q VXERUGHUV SRWHQWLDOO\ PDVNLQJ DQ\ GHWHFWDEOH OLQHDU WUHQG individually by order of their burial because there After their removal, the data set and regression were so few specimens in these categories. analysis gave a positive, but low correlation of Table 2 lists the means and medians for all 348 5 dinosaur taxa and selected suborders by geologic Both the theropods and the ornithopods exhibit series or depositional sequence. In this analysis, the the largest mean masses in the Upper Cretaceous PHDQLVSUREDEO\WKHPRVWVLJQLÀFDQWQXPEHUDVLW VWUDWD 7DEOH ,Q FRQWUDVW WKH VDXURSRGRPRUSKV minimizes the large mass ranges within the dinosaur VKRZ D SHDN LQ PHDQ PDVV LQ WKH 8SSHU -XUDVVLF groups. DQG D GUDPDWLF GURS LQ PHDQ PDVV LQ WKH ÀQDO 5HVXOWV VKRZ WKDW RQO\ VPDOOHU YDULHWLHV RI WZR GLQRVDXUEHDULQJ VHULHV 7KLV SHDN ZDV DOPRVW dinosaurs seem to have become buried in the lowest GRXEOHWKHPHDQPDVVRIWKHSUHYLRXVVHULHV 0LGGOH dinosaur-bearing strata. The mean mass for all -XUDVVLF DQG ZDV DJDLQ QHDUO\ GRXEOH WKH PHDQ dinosaur taxa buried in the Upper Triassic series PDVV RI HDFK VXEVHTXHQW VHULHV /RZHU DQG 8SSHU LV NJ OE ,Q WKH QH[W VWUDWXP DERYH WKH &UHWDFHRXV mean mass of all dinosaurs goes up dramatically, %HFDXVH WKH VDXURSRGRPRUSKV PDNH XS D ZLWK D PHDQ RI NJ OE LQ WKH /RZHU VXEVWDQWLDODPRXQWRIWKHGDWDVHW Q DQGWKHLU -XUDVVLFVHULHV7KLVWUHQGLQPHDQPDVVFRQWLQXHV mass distribution pattern was completely different WR LQFUHDVH WKURXJK WKH 0LGGOH -XUDVVLF NJ from the other suborders, we also calculated the >OE@ DQG8SSHU-XUDVVLF NJ>OE@ mass of all other dinosaur suborders collectively, VHULHV XQWLO WKH /RZHU &UHWDFHRXV ZKHQ WKH PHDQ H[FOXGLQJWKHVDXURSRGRPRUSKV 7DEOH 5HVXOWVRI GLQRVDXUPDVVGURSVWRNJ>OE@)LQDOO\WKH this analysis showed a different pattern with burial Table 2.0HDQVLQNJ PHGLDQLQSDUHQWKHVHV RIGLQRVDXUVE\JHRORJLFDOVHULHV Upper Lower Middle Upper Lower Upper Triassic Jurassic Jurassic Jurassic Cretaceous Cretaceous 1015 1,950 12,382 22,508 12,660 13,386 Sauropodomorphs (805) (460) (8900) (16,000) (11,500) (9050) 53 223 642 557 551 854 Theropods (16) (195) (560) (72) (20) (180) 17 16 20 301 2386 3093 Ornithopoda (17) (6) (7) (150) (800) (3200) 575 1097 6009 9866 3108 3221 All dinosaurs (30) (260) (1400) (2300) (260) (675) All dinosaurs 46 166 617 1216 1165 1782 (minus Sauropodomorphs) (31) (88) (360) (375) (51) (420) Determining Average Dinosaur Size Using the Most Recent Comprehensive Body Mass Data Set 89 compared to our earlier analysis of all the dinosaurs. shown in Fig. 3, there are many small dinosaurs in The mean mass of dinosaurs failed to show a clear, HYHU\ URFN OD\HU IURP WKH 8SSHU 7ULDVVLF WKURXJK systematic increase with time of burial even without the Upper Cretaceous, complicating statistical WKHLQÁXHQFHRIWKHVDXURSRGRPRUSKV$OWKRXJKWKH relationships. Fig. 3 does show the larger dinosaurs mean mass generally increases with time, there is getting larger with time, boosting the mean masses VWLOODQREVHUYDEOHGURSLQPHDQPDVVLQWKH/RZHU DQG FRQWULEXWLQJ WR WKH REVHUYHG ZHDN VWDWLVWLFDO Cretaceous series. VLJQLÀFDQFH%XWWKLVUHODWLRQVKLSLVVNHZHGE\WKH +RZHYHUZHGRQRWMXVWREVHUYHODUJHGLQRVDXUV YHU\ODUJHVWVDXURSRGRPRUSKVZKLFKSHDNHGLQWKH in the last of the dinosaur-bearing strata. As 8SSHU-XUDVVLF A Upper Cretaceous Lower Cretaceous Upper Jurassic Middle Jurassic Lower Jurassic Upper Triassic 0 0 10,000 20,000 30,000 40,000 50,000 60,000 Mass (kg) B Upper Cretaceous Lower Cretaceous Upper Jurassic Middle Jurassic Lower Jurassic Upper Triassic 0 0 2000 4000 6000 8000 10,000 12,000 14,000 16,000 18,000 Mass (kg) Fig. 3 $ 3ORWRIDOOLQGLYLGXDOGLQRVDXUPDVVHVE\JHRORJLFVWUDWD % 3ORWRIDOOLQGLYLGXDOGLQRVDXUPDVVHVE\ geologic strata omitting sauropodomorphs. 90 T. L. Clarey and J. P. Tomkins Discussion and Conclusions dinosaurs are found in the lowest dinosaur-bearing Where does this all lead? Are we any closer to strata because the larger ones were able to escape explaining the fossil record of dinosaurs? Yes and more readily. And yet, the largest sauropodomorphs no. Yes, we now have a fairly accurate median adult DUH IRXQG LQ /DWH -XUDVVLF URFNV QHDU WKH PLGGOH GLQRVDXUVL]HRINJ OE EDVHGRQWKHODUJHVW RI WKH GLQRVDXUEHDULQJ VWUDWD ,W LV OLNHO\ WKDW WKH most accurate survey of the currently available data sauropodomorphs could not run as fast or sustain on dinosaur taxa. This is a lot heavier than many travel as far as many of the other larger dinosaur earlier estimates of a dog or pony, and closer to JURXSV OLNH WKH RUQLWKRSRGV DQG WKH FHUDWRSVLDQV that of an American bison. We would suggest that As mentioned above, the sauropodomorphs also had creationists should be careful not to state that the the smallest brain-to-body ratios of any dinosaur “average” dinosaur was necessarily small. There suborder which probably caused them to react much ZHUHPDQ\VPDOOGLQRVDXUVEXWMXVWDVPDQ\ODUJH differently to the impending dangers of the rising dinosaurs, boosting the median size considerably. ZDWHU 7KH ODUJH KHUGV QXPEHULQJ WKRXVDQGV RI And no, there is no simple explanation to the RUQLWKRSRGV DQG FHUDWRSVLDQV WKDW OLNHO\ ZHUH YHU\ GLVWULEXWLRQ RI GLQRVDXUV LQ WKH )ORRG URFNV³WKH mobile and could sustain travel for great distances model is clearly multi-factor. In fact, Snelling are also found dominantly in the uppermost VXJJHVWHG WKHUH ZHUH DW OHDVW WKUHH IDFWRUV GLQRVDXUEHDULQJ URFNV RI WKH &UHWDFHRXV V\VWHP that determined the burial order of organisms in 0DQ\RIWKHODUJHVWWKHURSRGVDUHIRXQGLQWKHÀQDO WKH )ORRG WKHLU HOHYDWLRQ RI KDELWDW WKHLU GLQRVDXUEHDULQJ)ORRGVWUDWDDOVR,WZDVOLNHO\WKHLU UHDFWLRQ WR GDQJHU DQG SRVVLEO\ LQWHOOLJHQFH DQG combination of size, mobility, and intelligence that WKHLU PRELOLW\ ,I ZH DVVXPH WKH GLQRVDXUV ZHUH allowed them to survive as long as they did. It is no living at about the same elevation and habitat, we VXUSULVHWKHUHIRUHWRÀQGTyrannosaurus rex fossils FDQHVVHQWLDOO\HOLPLQDWHWKHÀUVWIDFWRUOHDYLQJXV near the top of Upper Cretaceous strata. with two main variables. A fairly similar elevation Dinosaur mobility may also explain why of habitat is possibly why dinosaurs are found only there appears to be an overrepresentation of LQOLPLWHG)ORRGVWUDWD H[FOXVLYHO\LQWKH0HVR]RLF theropod footprints compared to the bone record (UDWKHP 2EYLRXVO\ WKHUH ZDV VRPH YDULDWLRQ LQ RI WKHURSRGV %RQH IRVVLOV RI WKHURSRGV PDNH XS their habitat elevations, but overall, it may not have PXFKOHVVWKDQRIWKHGLQRVDXUIRVVLOV /RFNOH\ EHHQDVVLJQLÀFDQWDVWKHRWKHUWZRIDFWRUVGLVFXVVHG DQG +XQW 7UDFNV DW WKH 3XUJDWRLUH VLWH LQ below. &RORUDGR LQ -XUDVVLF V\VWHP URFNV VKRZ D Dinosaur reaction to danger may be partly related WKHURSRG SUHGDWRU WRVDXURSRGRPRUSK SUH\ to their intelligence. Dinosaurs exhibited large GLVWULEXWLRQ /RFNOH\DQG+XQW $QGWUDFNV YDULDWLRQV LQ EUDLQWRERG\ UDWLRV /XFDV ZLWKLQ WKH 'DNRWD *URXS &UHWDFHRXV V\VWHP 0RVW GLQRVDXU VXERUGHUV WKH VDXURSRGRPRUSKV QHDU 'HQYHU &RORUDGR DW 'LQRVDXU 5LGJH H[KLELW thyreophorans, and ceratopsians had relative proportions of 25–30% predator to 70–75% prey brain sizes much less than that of a modern lizard. /RFNOH\DQG+XQW Whereas, the ornithopods had relative brain Why the discrepancy between dinosaur footprint sizes similar to modern lizards, or slightly larger. data and the bone data? Higher activity levels of Theropods had the largest brain-to-body ratios of any WKHWKHURSRGVPD\EHWKHVROXWLRQ7KLVPDNHVHYHQ dinosaur group, with most of them possessing brains more sense if considered in a Flood context, however. ODUJHUWKDQDFRPSDUDEOHVL]HGOL]DUG EHWZHHQ² During the Flood, the theropods may have used WLPHVJUHDWHU /XFDV $QGWKHFRHOXURVDXUV their higher intelligence, speed, and agility levels to D VXEFDWHJRU\ RI WKH WKHURSRGV ZKLFK LQFOXGHV disproportionately escape the advancing Floodwaters WKH ´UDSWRUVµ KDG E\ IDU WKH ODUJHVW EUDLQV RI DQ\ DQGOHDYHPRUHWUDFNVFRPSDUHGWRWKHVORZHUDQG dinosaur category, with brains about 5.8 times larger less agile, plant eaters. This may be one reason why WKDQDFRPSDUDEOHPRGHUQOL]DUG /XFDV 7KH the proportion of theropod bones does not match the reason so many small coelurosaur dinosaurs were SURSRUWLRQRIWKHURSRGWUDFNV IRXQG LQ KLJKHU )ORRG VWUDWD OLNH WKH /RZHU DQG It appears there are competing and complicating Upper Cretaceous systems, may be because these factors to the order of dinosaur burial in the Flood. GLQRVDXUV ZHUH WKH PRVW LQWHOOLJHQW 7KH\ OLNHO\ Variables such as reaction to danger and mobility recognized and reacted to the dangers of the rising VHHP WR KDYH VWURQJO\ LQÁXHQFHG WKH EXULDO RUGHU )ORRGZDWHUVTXLFNHUDQGPRUHHIÀFLHQWO\WKDQPDQ\ of some dinosaur groups, and to a lesser degree, the other dinosaurs, and thus, survived longer before relative differences in habitat elevation. Although eventually succumbing to burial. some dinosaur groups seem to follow distinct Dinosaur mobility also probably played a big patterns, it may not be possible to sort out which UROH LQ VWUDWLÀFDWLRQ RI WKH GLQRVDXUV )HZ ODUJH factor was most dominant in every case. Determining Average Dinosaur Size Using the Most Recent Comprehensive Body Mass Data Set 91 ,WLVLQHYLWDEOHWKDWIXWXUHÀQGVRQGLQRVDXUERQHV &ULFKWRQ 0 The lost world. 1HZ