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Nipponoolithus
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<h2 id="distribution">Distribution</h2> <p><i>Nipponoolithus</i> remains are known from the Sasayama Group in Kamitaki, southeastern <a href="/facts/Tamba%2c_Hyogo/FBb78FIo">Tamba, Hyogo</a>, Japan. The site is dated to the lower <a href="/facts/Albian/faHcmHDC">Albian</a>.<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a> </p> <h2 id="history">History</h2> <p>Though fossil dinosaur skeletons are rare in Japan, they have been well-documented since <a href="/facts/1978_in_paleontology/qW7wYXAM">1978</a>.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a> The first Japanese fossil eggs were discovered in <a href="/facts/2003_in_paleontology/IdsXPCEf">2003</a>: Yoichi Azuma documented numerous eggs of the <a href="/facts/Egg_fossil/nH5XHNRS">Ratite morphotype</a> in the <a href="/facts/Kitadani_Formation/GlISlB1q">Kitadani Formation</a>,<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> and Ren Hirayama <i>et al.</i> documented dinosaur and turtle eggshells in the <a href="/facts/Kuwajima_Formation/gAGsk3mn">Kuwajima Formation</a>.<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a> However, these eggs were never described in detail.<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a> In <a href="/facts/2006_in_paleontology/CTGpXLxN">2006</a>, the dinosaur-rich Kamitaki locality in the Sasayama Group was discovered. In <a href="/facts/2016_in_paleontology/fB2K3Dqg">2016</a>, a team of paleontologists from Japan and Canada collected numerous fossilized eggs at Kamitaki, including the specimens which they would refer to a new oogenus and oospecies: <i>Nipponoolithus ramosus</i>.<a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a> </p> <h2 id="description">Description</h2> <p><i>Nipponoolithus ramosus</i> is known only from a handful of isolated eggshell fragments ranging from 0.36 to 0.53 mm in thickness, just barely larger than a chicken egg.<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a><a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a> It is estimated, based on the eggshell thickness, that <i>Nipponoolithus</i> eggs weighed about 100 grams (3.5 oz), making it among the smallest fossil dinosaur eggs ever discovered.<a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a> </p><p>Like most non-<a href="/facts/Bird/RJF6zwLP">avian</a> <a href="/facts/Dinosaur_eggs/bBypgTYQ">dinosaur eggs</a>, it has two layers:<a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a> the outer continuous layer, and the inner mammillary layer.<a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a> The continuous layer is two to four times thicker than the mammillary layer. <i>Nipponoolithus'</i>s outer surface is ornamented with low, branched ridges, similar to ornamentation observed in <i><a href="/facts/Macroelongatoolithus/ueLkkSCG">Macroelongatoolithus</a></i>, <i><a href="/facts/Montanoolithus/wrdBoscQ">Montanoolithus</a></i>, <i><a href="/facts/Paraelongatoolithus/Cn43tUXd">Paraelongatoolithus</a></i>, <i>Reticuloolithus</i>, <i>Spheruprismatoolithus</i>, and the eggs of <i><a href="/facts/Deinonychus/9zG2MVMC">Deinonychus</a></i>.<a class="footnote-ref" id="fnref:13" href="#fn:13"><sup>13</sup></a> The crystals in the mammillary layer are <a href="/facts/Acicular_(crystal_habit)/PGMnp4TX">acicular</a> or wedge-like.<a class="footnote-ref" id="fnref:14" href="#fn:14"><sup>14</sup></a> </p> <h2 id="paleobiology">Paleobiology</h2> <p><i>N. rumosus</i> was most likely laid by some kind of non-<a href="/facts/Bird/RJF6zwLP">avian</a> <a href="/facts/Maniraptor/X0NxnsBy">maniraptor</a> because of its similarities in microstructure and ornamentation to <a href="/facts/Oviraptorosaur/C6puS7KW">oviraptorosaur</a> eggs and the eggs of <i>Deinonychus</i>. Other very small theropod eggs (ranging in size from 27 grams (0.95 oz) to 135 grams (4.8 oz)), including <i><a href="/facts/Elongatoolithus/xjGwfIoF">Elongatoolithus</a></i>, <i><a href="/facts/Prismatoolithus/RrE4g0uc">Prismatoolithus</a></i> (and other indeterminate <a href="/facts/Prismatoolithus/RrE4g0uc">prismatoolithids</a>), as well as ornithopod eggs assigned to <i><a href="/facts/Spheroolithus/Ff3ty0tX">Spheroolithus</a></i>, are also known from the Kamitaki site. These eggs, along with skeletal remains, show that the parents of <i>Nipponoolithus</i> coexisted with numerous other small theropods, as well as an assemblage of <a href="/facts/Ankylosaur/lXPkLf0e">ankylosaurs</a>, <a href="/facts/Titanosaur/QzkgrcQR">titanosaurs</a>, <a href="/facts/Hadrosauroid/FJ49JytU">hadrosauroids</a>, <a href="/facts/Tyrannosaur/sIUowTnq">tyrannosaurs</a>, and <a href="/facts/Therizinosaur/0nRMf3uj">therizinosaurs</a>. The parent of <i>Nipponoolithus</i> probably weighed roughly 15 kilograms (33 lb), comparable to the size of some contemporary small theropods from the <a href="/facts/Jehol_biota/YmjQMeWc">Jehol biota</a> in China.<a class="footnote-ref" id="fnref:15" href="#fn:15"><sup>15</sup></a> </p> <h2 id="parataxonomy">Parataxonomy</h2> <p><i>Nipponoolithus</i> has not been place into any described oofamily. It contains a single oospecies: <i>N. ramosus</i>.<a class="footnote-ref" id="fnref:16" href="#fn:16"><sup>16</sup></a> </p> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>Tanaka, K., Zelenitsky, D. K., Saegusa, H., Ikeda, T., DeBuhr, C. L., & Therrien, F. (2016). Dinosaur eggshell assemblage from Japan reveals unknown diversity of small theropods. Cretaceous Research, 57, 350–363. <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Tanaka, K., Zelenitsky, D. K., Saegusa, H., Ikeda, T., DeBuhr, C. L., & Therrien, F. (2016). Dinosaur eggshell assemblage from Japan reveals unknown diversity of small theropods. Cretaceous Research, 57, 350–363. <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>Tanaka, K., Zelenitsky, D. K., Saegusa, H., Ikeda, T., DeBuhr, C. L., & Therrien, F. (2016). Dinosaur eggshell assemblage from Japan reveals unknown diversity of small theropods. Cretaceous Research, 57, 350–363. <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>Azuma, Y. (2003). "Early Cretaceous vertebrate remains from Katsuyama city, Fukui Prefecture, Japan." Memoir of the Fukui Prefectural Dinosaur Museum, 2: 17–21 <a href="http://www.dinosaur.pref.fukui.jp/archive/memoir/memoir002-017.pdf" target="_blank">http://www.dinosaur.pref.fukui.jp/archive/memoir/memoir002-017.pdf</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>Hirayama, R., Manabe, M., Isaji, S., Barrett, P.M., Evans, S.E., Yabumoto, Y., Matsuoka, H., Yamaguchi, I., Yamaguchi, M., (2003) "Vertebrate fauna from the Early Cretaceous Kuwajima Formation of Shiramine Village, Ishikawa Prefecture, central Japan." Memoir of the Fukui Prefectural Dinosaur Museum, 2: 15–16 <a href="http://www.dinosaur.pref.fukui.jp/archive/memoir/memoir002-015.pdf" target="_blank">http://www.dinosaur.pref.fukui.jp/archive/memoir/memoir002-015.pdf</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>Tanaka, K., Zelenitsky, D. K., Saegusa, H., Ikeda, T., DeBuhr, C. L., & Therrien, F. (2016). Dinosaur eggshell assemblage from Japan reveals unknown diversity of small theropods. Cretaceous Research, 57, 350–363. <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>Tanaka, K., Zelenitsky, D. K., Saegusa, H., Ikeda, T., DeBuhr, C. L., & Therrien, F. (2016). Dinosaur eggshell assemblage from Japan reveals unknown diversity of small theropods. Cretaceous Research, 57, 350–363. <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>Tanaka, K., Zelenitsky, D. K., Saegusa, H., Ikeda, T., DeBuhr, C. L., & Therrien, F. (2016). Dinosaur eggshell assemblage from Japan reveals unknown diversity of small theropods. Cretaceous Research, 57, 350–363. <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>Miller, KK (2015). "World’s smallest dinosaur egg just discovered in Hyogo Prefecture" Rocket News 24. <a href="http://en.rocketnews24.com/2015/07/01/worlds-smallest-dinosaur-egg-just-discovered-in-hyogo-prefecture/" target="_blank">http://en.rocketnews24.com/2015/07/01/worlds-smallest-dinosaur-egg-just-discovered-in-hyogo-prefecture/</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> <li id="fn:10"><p>Tanaka, K., Zelenitsky, D. K., Saegusa, H., Ikeda, T., DeBuhr, C. L., & Therrien, F. (2016). Dinosaur eggshell assemblage from Japan reveals unknown diversity of small theropods. Cretaceous Research, 57, 350–363. <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li> <li id="fn:11"><p>Laura E. Wilson, Karen Chin, Frankie D. Jackson, and Emily S. Bray. II. Eggshell morphology and structure. UCMP Online Exhibits: Fossil Eggshell <a href="http://www.ucmp.berkeley.edu/science/eggshell/eggshell2.php" target="_blank">http://www.ucmp.berkeley.edu/science/eggshell/eggshell2.php</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li> <li id="fn:12"><p>Tanaka, K., Zelenitsky, D. K., Saegusa, H., Ikeda, T., DeBuhr, C. L., & Therrien, F. (2016). Dinosaur eggshell assemblage from Japan reveals unknown diversity of small theropods. Cretaceous Research, 57, 350–363. <a href="#fnref:12" class="footnote-back-ref">↩</a></p></li> <li id="fn:13"><p>Tanaka, K., Zelenitsky, D. K., Saegusa, H., Ikeda, T., DeBuhr, C. L., & Therrien, F. (2016). Dinosaur eggshell assemblage from Japan reveals unknown diversity of small theropods. Cretaceous Research, 57, 350–363. <a href="#fnref:13" class="footnote-back-ref">↩</a></p></li> <li id="fn:14"><p>Tanaka, K., Zelenitsky, D. K., Saegusa, H., Ikeda, T., DeBuhr, C. L., & Therrien, F. (2016). Dinosaur eggshell assemblage from Japan reveals unknown diversity of small theropods. Cretaceous Research, 57, 350–363. <a href="#fnref:14" class="footnote-back-ref">↩</a></p></li> <li id="fn:15"><p>Tanaka, K., Zelenitsky, D. K., Saegusa, H., Ikeda, T., DeBuhr, C. L., & Therrien, F. (2016). Dinosaur eggshell assemblage from Japan reveals unknown diversity of small theropods. Cretaceous Research, 57, 350–363. <a href="#fnref:15" class="footnote-back-ref">↩</a></p></li> <li id="fn:16"><p>Tanaka, K., Zelenitsky, D. K., Saegusa, H., Ikeda, T., DeBuhr, C. L., & Therrien, F. (2016). Dinosaur eggshell assemblage from Japan reveals unknown diversity of small theropods. Cretaceous Research, 57, 350–363. <a href="#fnref:16" class="footnote-back-ref">↩</a></p></li> </ol>