[dinosaur] Body size distributions in crocodyliformes + giant ground sloth mass death site
Ben Creisler <[email protected]> Mon, 13 Jan 2020 17:40:36 -0800
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--00000000000075331b059c0faeeb Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: Quoted-printable Ben Creisler [email protected] Some new non-dino papers: William Gearty & Jonathan L. Payne (2020) Physiological constraints on body size distributions in crocodyliformes. Evolution (advance online publication) doi: https://urldefense.proofpoint.com/v2/url?u=3Dhttps-3A__doi.org_10.1111= _evo.13901&d=3DDwIFaQ&c=3DclK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=3DR= y_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=3DWWZqG7ZqkQ9qmD8PRFHCcMnCRjuw= QhksWTocq0RxWY8&s=3DCaTRLc9a7gHjMiXm6jwCoz6zNFBoZI0jtkzRe07o7eA&e=3D=20 https://urldefense.proofpoint.com/v2/url?u=3Dhttps-3A__onlinelibrary.wiley.= com_doi_10.1111_evo.13901&d=3DDwIFaQ&c=3DclK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p= 7CSfnc_gI&r=3DRy_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=3DWWZqG7ZqkQ9qm= D8PRFHCcMnCRjuwQhksWTocq0RxWY8&s=3DIEJeAW-qE96g-0ZOO16WJAOK6h-N9NVbyScyhDDJ= a9Y&e=3D=20 At least twenty=E2=80=90six species of crocodylian populate the globe today= , but this richness represents a minute fraction of the diversity and disparity of Crocodyliformes. Fossil forms are far more varied, spanning from erect, fully terrestrial species to flippered, fully marine species. To quantify the influence of a marine habitat on the directionality, rate, and variance of evolution of body size in Crocodyliformes and thereby identify underlying selective pressures, we compiled a database of body sizes for 264 fossil and modern species of crocodyliform covering terrestrial, semi=E2=80=90aquatic, and marine habitats. We find increases in body size c= oupled with increases in strength of selection and decreases in variance following invasions of marine habitats but not of semi=E2=80=90aquatic habitats. A mo= del combining constraints from thermoregulation and lung capacity provides a physiological explanation for the larger minimum and average sizes of marine species. It appears that constraints on maximum size are shared across Crocodyliformes, perhaps through factors such as the allometric scaling of feeding rate versus basal metabolism with body size. These findings suggest that broad=E2=80=90scale patterns of body size evolution a= nd the shapes of body size distributions within higher taxa are often determined more by physiological constraints than by ecological interactions or environmental fluctuations. =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D Emily L. Lindsey, Erick X. Lopez Reyes, Gordon E. Matzke, Karin A. Rice & H. Gregory McDonald (2020) A monodominant late-Pleistocene megafauna locality from Santa Elena, Ecuador: Insight on the biology and behavior of giant ground sloths Palaeogeography, Palaeoclimatology, Palaeoecology (advance online publication) doi: https://urldefense.proofpoint.com/v2/url?u=3Dhttps-3A__doi.org_10.1016= _j.palaeo.2020.109599&d=3DDwIFaQ&c=3DclK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSf= nc_gI&r=3DRy_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=3DWWZqG7ZqkQ9qmD8PR= FHCcMnCRjuwQhksWTocq0RxWY8&s=3DjM2J_tlzcQqBzKTBK97ILlJLAu-iQKWrXri0MJTwhYY&= e=3D=20 https://urldefense.proofpoint.com/v2/url?u=3Dhttps-3A__www.sciencedirect.co= m_science_article_abs_pii_S003101821930447X&d=3DDwIFaQ&c=3DclK7kQUTWtAVEOVI= gvi0NU5BOUHhpN0H8p7CSfnc_gI&r=3DRy_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI= &m=3DWWZqG7ZqkQ9qmD8PRFHCcMnCRjuwQhksWTocq0RxWY8&s=3DFyhbAmlcIMKHSaZ6Bjc8S9= JU64OEUl-1CBPow7r0-a4&e=3D=20 Highlights We document an apparent mass-death assemblage of Eremotherium giant ground sloths. This multigenerational group likely congregated and died in a shallow marsh. The die-off may have been caused by contamination of the wallow by fecal material. Some ground sloths may have been ecologically similar to modern hippos. Some species of ground sloths may have been gregarious. Abstract Extinct giant ground sloths are a common taxon in New World Quaternary deposits, but relatively little is known about individual species' behavior or social structure. In this paper, we investigate the development of the late-Pleistocene locality Tanque Loma on the southwest coast of Ecuador, which preserves remains of at least 22 individuals of the giant ground sloth, Eremotherium laurillardi in asphaltic sediments. Multiple lines of evidence suggest that these sloths may have congregated and died in a mass mortality event in a marshy riparian habitat. Such evidence includes (1) a dense, laterally-extensive, bonebed-style accumulation; (2) a multigenerational age structure with adult and large juvenile individuals well-represented; (3) sediments suggestive of a low-energy anoxic aquatic environment; and (4) the presence of abundant plant material consistent with digested fodder representing coprolites or gut contents of E. laurillardi. Taking observations from modern megafaunal ecosystems as an analogue, we suggest that this death event could have resulted from drought and/or disease stemming from the contamination of the wallow, paralleling situations observed among hippopotamus populations in watering holes on the present-day African savannah. =3D=3D=3D=3D=3D --00000000000075331b059c0faeeb Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: Quoted-printable <div dir=3D"ltr"><div><br></div>Ben Creisler<div><a href=3D"mailto:bcreisle= [email protected]">[email protected]</a></div><div><br></div><div>Some new non-= dino papers:<br><div><br></div><div><br></div><div>William Gearty =C2=A0&am= p; Jonathan L. Payne (2020)<br>Physiological constraints on body size distr= ibutions in crocodyliformes.<br>Evolution (advance online publication)<br>d= oi: <a href=3D"https://urldefense.proofpoint.com/v2/url?u=3Dhttps-3A__doi.o= rg_10.1111_evo.13901&d=3DDwMFaQ&c=3DclK7kQUTWtAVEOVIgvi0NU5BOUHhpN0= H8p7CSfnc_gI&r=3DRy_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=3DWW= ZqG7ZqkQ9qmD8PRFHCcMnCRjuwQhksWTocq0RxWY8&s=3DCaTRLc9a7gHjMiXm6jwCoz6zN= FBoZI0jtkzRe07o7eA&e=3D">https://doi.org/10.1111/evo.13901</a><br><a hr= ef=3D"https://urldefense.proofpoint.com/v2/url?u=3Dhttps-3A__onlinelibrary.= wiley.com_doi_10.1111_evo.13901&d=3DDwMFaQ&c=3DclK7kQUTWtAVEOVIgvi0= NU5BOUHhpN0H8p7CSfnc_gI&r=3DRy_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI= &m=3DWWZqG7ZqkQ9qmD8PRFHCcMnCRjuwQhksWTocq0RxWY8&s=3DIEJeAW-qE96g-0= ZOO16WJAOK6h-N9NVbyScyhDDJa9Y&e=3D">https://onlinelibrary.wiley.com/doi= /10.1111/evo.13901</a></div><div><br></div><div><br></div><div><br>At least= twenty=E2=80=90six species of crocodylian populate the globe today, but th= is richness represents a minute fraction of the diversity and disparity of = Crocodyliformes. Fossil forms are far more varied, spanning from erect, ful= ly terrestrial species to flippered, fully marine species. To quantify the = influence of a marine habitat on the directionality, rate, and variance of = evolution of body size in Crocodyliformes and thereby identify underlying s= elective pressures, we compiled a database of body sizes for 264 fossil and= modern species of crocodyliform covering terrestrial, semi=E2=80=90aquatic= , and marine habitats. We find increases in body size coupled with increase= s in strength of selection and decreases in variance following invasions of= marine habitats but not of semi=E2=80=90aquatic habitats. A model combinin= g constraints from thermoregulation and lung capacity provides a physiologi= cal explanation for the larger minimum and average sizes of marine species.= It appears that constraints on maximum size are shared across Crocodylifor= mes, perhaps through factors such as the allometric scaling of feeding rate= versus basal metabolism with body size. These findings suggest that broad= =E2=80=90scale patterns of body size evolution and the shapes of body size = distributions within higher taxa are often determined more by physiological= constraints than by ecological interactions or environmental fluctuations.= <br><br><br></div><div>=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D</div><div><b= r></div><div><br>Emily L. Lindsey, Erick X. Lopez Reyes, Gordon E. Matzke, = Karin A. Rice & H. Gregory McDonald (2020)<br>A monodominant late-Pleis= tocene megafauna locality from Santa Elena, Ecuador: Insight on the biology= and behavior of giant ground sloths<br>Palaeogeography, Palaeoclimatology,= Palaeoecology (advance online publication)<br>doi: <a href=3D"https://urld= efense.proofpoint.com/v2/url?u=3Dhttps-3A__doi.org_10.1016_j.palaeo.2020.10= 9599&d=3DDwMFaQ&c=3DclK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&= ;r=3DRy_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=3DWWZqG7ZqkQ9qmD8PRF= HCcMnCRjuwQhksWTocq0RxWY8&s=3DjM2J_tlzcQqBzKTBK97ILlJLAu-iQKWrXri0MJTwh= YY&e=3D">https://doi.org/10.1016/j.palaeo.2020.109599</a> <br><a href= =3D"https://urldefense.proofpoint.com/v2/url?u=3Dhttps-3A__www.sciencedirec= t.com_science_article_abs_pii_S003101821930447X&d=3DDwMFaQ&c=3DclK7= kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=3DRy_mO4IFaUmGof_Yl9MyZgecRCK= Hn5g4z1CYJgFW9SI&m=3DWWZqG7ZqkQ9qmD8PRFHCcMnCRjuwQhksWTocq0RxWY8&s= =3DFyhbAmlcIMKHSaZ6Bjc8S9JU64OEUl-1CBPow7r0-a4&e=3D">https://www.scienc= edirect.com/science/article/abs/pii/S003101821930447X</a><br><br>Highlights= </div><div><br>We document an apparent mass-death assemblage of Eremotheriu= m giant ground sloths.<br>This multigenerational group likely congregated a= nd died in a shallow marsh.<br>The die-off may have been caused by contamin= ation of the wallow by fecal material.<br>Some ground sloths may have been = ecologically similar to modern hippos.<br>Some species of ground sloths may= have been gregarious.<br><br><br>Abstract</div><div><br>Extinct giant grou= nd sloths are a common taxon in New World Quaternary deposits, but relative= ly little is known about individual species' behavior or social structu= re. In this paper, we investigate the development of the late-Pleistocene l= ocality Tanque Loma on the southwest coast of Ecuador, which preserves rema= ins of at least 22 individuals of the giant ground sloth, Eremotherium laur= illardi in asphaltic sediments. Multiple lines of evidence suggest that the= se sloths may have congregated and died in a mass mortality event in a mars= hy riparian habitat. Such evidence includes (1) a dense, laterally-extensiv= e, bonebed-style accumulation; (2) a multigenerational age structure with a= dult and large juvenile individuals well-represented; (3) sediments suggest= ive of a low-energy anoxic aquatic environment; and (4) the presence of abu= ndant plant material consistent with digested fodder representing coprolite= s or gut contents of E. laurillardi. Taking observations from modern megafa= unal ecosystems as an analogue, we suggest that this death event could have= resulted from drought and/or disease stemming from the contamination of th= e wallow, paralleling situations observed among hippopotamus populations in= watering holes on the present-day African savannah.<br><br>=3D=3D=3D=3D=3D= <br></div><div><br></div></div></div> --00000000000075331b059c0faeeb--