Macroelongatoolithus

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Macroelongatoolithus
Temporal range: Cretaceous, 145–66  Ma
Eier des Tarbosaurus.JPG
Macroelongatoolithus eggs in the Naturhistorisches Museum Wien
Egg fossil classification OOjs UI icon edit-ltr.svg
Basic shell type: Ornithoid
Morphotype: Ornithoid-ratite
Oofamily:† Elongatoolithidae
Oogenus:† Macroelongatoolithus
Li et al., 1995
Synonyms
Oogenus synonymy
  • BoletuoolithusBray, 1998
  • LongiteresoolithusWang and Zhou, 1995
  • MegafusoolithusWang et al, 2010
Oospecies synonymy
  • Oolithes carlylensis Jensen, 1970
  • Megafusoolithus qiaoxiaensisWang et al, 2010
  • Longiteresoolithus xixiaensisWang and Zhou, 1995
  • Macroelongatoolithus xixiaensisLi et al, 1995
  • Macroelongatoolithus zhangiFang et al, 2000
  • Macroelongatoolithus goseongensisKim et al, 2011

Macroelongatoolithus is an oogenus of large theropod dinosaur eggs, representing the eggs of giant caenagnathid oviraptorosaurs. They are known from Asia and from North America. Historically, several oospecies have been assigned to Macroelongatoolithus, however they are all now considered to be a single oospecies: M. carlylensis.

Contents

History of discovery

Macroelongatoolithus nest (MNHM-nat201153) from Aphaedo Island, South Korea sinan abhaedo sugagryu gongryongaldungji hwaseog 1.jpg
Macroelongatoolithus nest (MNHM-nat201153) from Aphaedo Island, South Korea

"Oolithes" carlylensis was described in 1970 by James Jensen. [1] In 1998, O. carlylensis was moved to a new oogenus, Boletuoolithus, which was then classified as a Spheroolithid. [2] Macroelongatoolithus was first described in 1995 by Li et al., with a single oospecies: M. xixiaensis. It was classified in the oofamily Elongatoolithidae. [3] Later in the same year, Wang and Zhou described Longiteresoolithus xixiaensis, which they placed into a new oofamily, Macroelongatoolithidae. These three oospecies are now considered synonymous, and generally classified in Elongatoolithidae. Since M. carlylensis was named first, it has priority, but the name was corrected to M.carlylei to follow ICZN provisions. [4] [5]

Description

Eggshell surface (a) and microstructure (b) of Macroelongatoolithus eggs associated with Beibeilong Eggshell associated with Beibeilong sinensis (HGM 41HIII1219).jpg
Eggshell surface (a) and microstructure (b) of Macroelongatoolithus eggs associated with Beibeilong

Macroelongatoolithus eggs are most notable for their large size. They are at least 34 centimetres (13 in) long, but the largest specimens are over 60 centimetres (24 in) long. [6] [4] [7] They are also very elongated, usually roughly three times longer than they are wide. They are often found in large clutches of up to 26 eggs, with the eggs forming a ring 2–3.3 metres (6.6–10.8 ft) in diameter. The shell is typically between 1.38 mm and 4.75 mm thick. [4] [5] [8]

Like other elongatoolithids, Macroelongatoolithus's eggshell is divided up into two structural layers, and the outer layer (called the continuous layer) is not divided up into distinct shell units, unlike other oofamilies. In Macroelongatoolithus, the boundary between the continuous layer and the mammillary layer (the inner layer of the eggshell, also called the cone layer) is wavy, but clearly defined. The ratio of the thickness of the two layers varies from 2:1 to 8:1. [4] [8]

The surface ornamentation of the eggshells is variable, even on a single egg. It is usually lineartuberculate (nodes forming linear ridges), ramotuberculate (nodes forming irregular, meandering chains), or dispersituberculate (scattered nodes). [4] [8]

Macroelongatoolithus specimens are extremely variable in size, shape, and microstructure, even in eggs laid by a single individual. For example, within a single clutch, the egg lengths can vary by several centimeters. The high amount of variability is probably due to their large size. [5]

Classification

Macroelongatoolithus has a convoluted parataxonomic history. Several oospecies have been described, but currently they are all considered synonyms of M. carlylei. While it is occasionally classified into a separate oofamily, Macroelongatoolithidae, the general consensus is that it is a member of Elongatoolithidae. [4] Two other oospecies have also been described: M. zhangi and M. goseongensis, but both are now considered synonymous with M. carlylensis. [4] The oogenus and oospecies Megafusoolithus qiaoxiaensis is also a junior synonym of Macroelongatoolithus carlylei. [4]

Paleobiology

Macroelongatoolithus (41HV003-16) nest with eggs Macroelongatoolithus nest HGM 41HIII1219.jpg
Macroelongatoolithus (41HV003-16) nest with eggs

While they were once considered to be the eggs of large tyrannosaurids (like Tarbosaurus ) on the basis of their huge size, [9] egg shape and microstructural evidence suggests they are eggs of gigantic oviraptorosaurs (like Beibeilong or Gigantoraptor ). [7] Macroelongatoolithus eggs closely resemble those of oviraptorids (Elongatoolithidae), [10] which are largely known for their brooding adult-nest associations, embryonic remains, and unique nests. [4] In 2017 the caenagnathid Beibeilong was described, based on an embryonic specimen (named "Baby Louie") associated with 6 to 8 Macroelongatoolithus eggs and partial nest. The discovery of Beibeilong further concludes that the oogenus Macroelongatoolithus was laid by large oviraptorosaurs, in this case caenagnathids. [7]

The gas conductance of the eggshells indicate that Macroelongatoolithus nests were buried in vegetation or sediments. Like other elongatoolithids, Macroelongatoolithus eggs are laid in pairs because the parents had two functional oviducts and thus laid two eggs simultaneously. The nests have unusually large volume of eggs compared to the body size of the parents, which could mean that multiple females would contribute to a single nest. Association of other oviraptorids with their eggs suggests extensive parental care was typical for elongatoolithids. [4]

Reconstructed Gigantoraptor nest, American Museum of Natural History Gigantoraptor nest.jpg
Reconstructed Gigantoraptor nest, American Museum of Natural History

In 2018, Kohei Tanaka and team examined the egg clutches of numerous oviraptorosaur specimens, including egg clutches of Macroelongatoolithus, in order to correlate the nest configuration and body size to incubation behaviour. Their results showed that eggshell porosity indicates that the eggs of almost certainly all oviraptorosaurs were exposed in the nest without an external covering. Though most oviraptorosaur nests have eggs arranged in a circular fashion, the morphology of the nest is different in smaller and larger species in that the center of the nest is highly reduced in the former species, and becomes significantly larger in the latter species. This nest configuration suggest that whereas smallest oviraptorosaurs probably sat directly on the eggs, a large, Gigantoraptor-sized animal likely sat on the area devoid of eggs. Tanaka and colleagues pointed out that this adaption was beneficial to avoid egg-crushing and could have allowed some body-contact during incubation in these giant oviraptorosaurs. [11]

Paleoecology

Distribution

Macroelongatoolithus eggs have been found in the United States, China, and South Korea, ranging in age from Early Cretaceous to Maastrichtian. [4] More specifically, it is known in North America from the Cedar Mountain, Dakota, and Kelvin Formations of Utah, [5] the Wayan Formation of Idaho, the Blackleaf Formation of Montana, the Thomas Fork Formation of Wyoming, [4] and the Willow Tank Formation of Nevada. [12] In China, it is known from the Liangtoutang and Chichengshan Formations in Tiantai County, Zhejiang Province, [13] [14] from the Gaogou, Sigou, Majiacun, and Zoumagang Formations in Henan Province, China. [4] [10] [15] It is known in South Korea from the Goseong Formation near Tongyeong and from Aphae-do in Shinan-gun, Jeollanam-do Province. [16] [17]

The presence of Macroelongatoolithus in the United States indicates that there was likely a giant oviraptorosaur present during the Late Cretaceous in North America. Also, the fact that they have been found in both Asia and North America is evidence of an Albian-Cenomanian interchange of fauna between the two continents. [5] [4] [8]

See also

Related Research Articles

<i>Gigantoraptor</i> Extinct genus of dinosaurs

Gigantoraptor is a genus of large oviraptorosaur dinosaur that lived in Asia during the Late Cretaceous period. It is known from the Iren Dabasu Formation of Inner Mongolia, where the first remains were found in 2005.

<i>Elongatoolithus</i> Fossil dinosaur eggs

Elongatoolithus is an oogenus of dinosaur eggs found in the Late Cretaceous formations of China and Mongolia. Like other elongatoolithids, they were laid by small theropods, and were cared for and incubated by their parents until hatching. They are often found in nests arranged in multiple layers of concentric rings. As its name suggests, Elongatoolithus was a highly elongated form of egg. It is historically significant for being among the first fossil eggs given a parataxonomic name.

<i>Macroolithus</i> Oogenus of dinosaur egg

Macroolithus is an oogenus of dinosaur egg belonging to the oofamily Elongatoolithidae. The type oospecies, M. rugustus, was originally described under the now-defunct oogenus name Oolithes. Three other oospecies are known: M. yaotunensis, M. mutabilis, and M. lashuyuanensis. They are relatively large, elongated eggs with a two-layered eggshell. Their nests consist of large, concentric rings of paired eggs. There is evidence of blue-green pigmentation in its shell, which may have helped camouflage the nests.

Phaceloolithus is an oogenus of dinosaur egg found in the Fenshui'ao Formation of the Dongting Basin of the Hunan Province of China. The eggs have a subspherical shape, measuring up to 168 mm on the long axis, and having a very thin shell.

Continuoolithus is an oogenus of dinosaur egg found in the late Cretaceous of North America. It is most commonly known from the late Campanian of Alberta and Montana, but specimens have also been found dating to the older Santonian and the younger Maastrichtian. It was laid by an unknown type of theropod. These small eggs are similar to the eggs of oviraptorid dinosaurs, but have a distinctive type of ornamentation.

Dispersituberoolithus is an oogenus of fossil egg, which may have been laid by a bird or non-avian theropod.

Porituberoolithus is an oogenus of dinosaur egg found in the late Campanian Oldman Formation and Dinosaur Park Formation of Alberta, the Fossil Forest Member of the Fruitland Formation in New Mexico, the Upper Shale Member of the Aguja Formation in Texas and Cerro del Pueblo Formation of Mexico. It was originally described as distinct from the Elongatoolithids on the basis of its ornamentation, but it was listed as a member of that oofamily by Wang et al. 2010. It is very similar to Subtiliolithus, but has a thicker shell.

<span class="mw-page-title-main">Egg fossil</span> Fossilized remains of eggs laid by ancient animals

Egg fossils are the fossilized remains of eggs laid by ancient animals. As evidence of the physiological processes of an animal, egg fossils are considered a type of trace fossil. Under rare circumstances a fossil egg may preserve the remains of the once-developing embryo inside, in which case it also contains body fossils. A wide variety of different animal groups laid eggs that are now preserved in the fossil record beginning in the Paleozoic. Examples include invertebrates like ammonoids as well as vertebrates like fishes, possible amphibians, and reptiles. The latter group includes the many dinosaur eggs that have been recovered from Mesozoic strata. Since the organism responsible for laying any given egg fossil is frequently unknown, scientists classify eggs using a parallel system of taxonomy separate from but modeled after the Linnaean system. This "parataxonomy" is called veterovata.

Montanoolithus is an oogenus of fossil egg found in Montana and Alberta. They were probably laid by a dromaeosaur or a caenagnathid.

Paraelongatoolithus is a late Cretaceous oogenus of Chinese fossil egg, classified in the oofamily Elongatoolithidae, which represents the eggs of oviraptorosaurs.

Heishanoolithus is an oogenus of Elongatoolithid fossil egg from the Shahai Formation in Liaoning. It is known only from seven eggshell fragments. It is most notable for having a very thin eggshell, the dense covering of nodes on the eggshell surface, and for its relatively thin mammilary layer. While no remains of Heishanoolithus have been associated with skeletal remains, strong evidence links Elongatoolithid eggs to Oviraptorosaurs.

<span class="mw-page-title-main">Elongatoolithidae</span> Oofamily of dinosaur eggs

Elongatoolithidae is an oofamily of fossil eggs, representing the eggs of oviraptorosaurs. They are known for their highly elongated shape. Elongatoolithids have been found in Europe, Asia, and both North and South America.

Guegoolithus is an oogenus of fossil egg from the early Cretaceous of Spain. It is classified in the oofamily Spheroolithidae, and was probably laid by an ornithopod dinosaur.

Undulatoolithus is an oogenus of Chinese fossil dinosaur egg belonging to Elongatoolithidae. It is very similar to Macroolithus, but has different ornamentation. Like other elongatoolithids, it was probably laid by oviraptorosaurs.

Dictyoolithidae is an oofamily of dinosaur eggs which have a distinctive reticulate organization of their eggshell units. They are so far known only from Cretaceous formations in China.

Triprismatoolithus is an oogenus of dinosaur egg native to Teton County, Montana. It is classified in the oofamily Arriagadoolithidae, the eggs of alvarezsaurs.

Nipponoolithus is an oogenus of fossil egg native to Japan. It is one of the smallest known dinosaur eggs, and was probably laid by some kind of non-avian maniraptor.

<i>Beibeilong</i> Caenagnathid dinosaur genus from the Late Cretaceous

Beibeilong is a genus of large caenagnathid dinosaurs that lived in Asia during the Late Cretaceous epoch, about 96 million to 88 million years ago. The genus contains a single species, Beibeilong sinensis. The species was named and described in 2017 through analysis of an embryonic skeleton and partial nest with large eggs that were discovered in the Gaogou Formation of China between 1992 and 1993.

Nanhsiungoolithus is an oogenus of dinosaur egg from the late Cretaceous of China. It belongs to the oofamily Elongatoolithidae, which means that it was probably laid by an oviraptorosaur, though so far no skeletal remains have been discovered in association with Nanhsiungoolithus. The oogenus contains only a single described oospecies, N. chuetienensis. It is fairly rare, only being know from two partially preserved nests and a few eggshell fragments.

D. Jade Simon is an American paleontologist, scientific communicator, and disability rights advocate. She is currently a Ph.D. candidate at the University of Toronto, where she studies the paleobiology of oviraptorosaur dinosaurs.

References

  1. ↑ Jensen J. 1970. Fossil eggs in the lower cretaceous of Utah. Brigham Young University research studies. Geology Series. Geology Studies 17: 51-65.
  2. ↑ Bray, E. S. 1998. Dinosaur eggshell Boletuoolithus carlylensis, oogen. nov. from the Lower Cretaceous Cedar Mountain Formation of Utah; pp. 221–223 in S. G. Lucas, J. I. Kirkland, and J. W. Estep (eds.), Lower and Middle Cretaceous Terrestrial Ecosystems. New Mexico Museum of Natural History and Science Bulletin No. 14.
  3. ↑ Li Y, Yin Z, Liu Y. (1995) "The discovery of a new genus of dinosaur egg from Xixia, Henan, China." Journal of Wuhan Institute of Chemical Technology 17(1): 38-41. (In Chinese)
  4. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Simon, D. J. (2014). "Giant Dinosaur (theropod) Eggs of the Oogenus Macroelongatoolithus (Elongatoolithidae) from Southeastern Idaho: Taxonomic, Paleobiogeographic, and Reproductive Implications" (PDF). Doctoral Dissertation, Montana State University. Bozeman. Archived (PDF) from the original on 11 August 2021.
  5. 1 2 3 4 5 Zelenitsky DK, Carpenter K, Currie PJ. (2000) "First record of Elongatoolithid theropod eggshell from North America: the Asian oogenus Macroelongatoolithus from the lower Cretaceous of Utah." Journal of Vertebrate Paleontology 20(1): 130-138.
  6. ↑ Carpenter, K. 1999. Eggs, Nests, and Baby Dinosaurs: A Look at Dinosaur Reproduction (Life of the Past). Indiana University Press, Bloomington, Indiana.
  7. 1 2 3 Pu, H.; Zelenitsky, D. K.; Lü, J.; Currie, P. J.; Carpenter, K.; Xu, L.; Koppelhus, E. B.; Jia, S.; Xiao, L.; Chuang, H.; Li, T.; Kundrát, M.; Shen, C. (2017). "Perinate and eggs of a giant caenagnathid dinosaur from the Late Cretaceous of central China". Nature Communications. 8 (14952): 14952. Bibcode:2017NatCo...814952P. doi: 10.1038/ncomms14952 . PMC   5477524 . PMID   28486442.
  8. 1 2 3 4 Simon, D. J.; Varricchio, D. J.; Jin, X.; Robinson, S. F. (2019). "Microstructural overlap of Macroelongatoolithus eggs from Asia and North America expands the occurrence of colossal oviraptorosaurs". Journal of Vertebrate Paleontology. 38 (6): e1553046. doi:10.1080/02724634.2018.1553046. S2CID   191155027.
  9. ↑ Qian, M. P., Jiang, Y., Jiang, Y. G., Zhang, Y. J., Chen, R., Li, L. M., and Xing, G. F. (2008). "New evidence on fossil eggs of Cretaceous Tyrannosaurs in eastern China." Jiangsu Geology, 32: 86-97.
  10. 1 2 Grellet-Tinner, G., Chiappe, L., Norell, M., and Bottjer, D. (2006). "Dinosaur eggs and nesting behaviors: a paleobiological investigation." Palaeogeography, Palaeoclimatology, Palaeoecology, 232(2): 294-321.
  11. ↑ Tanaka, K.; Zelenitsky, D. K.; Lü, J.; DeBuhr, C. L.; Yi, L.; Jia, S.; Ding, F.; Xia, M.; Liu, D.; Shen, C.; Chen, R. (2018). "Incubation behaviours of oviraptorosaur dinosaurs in relation to body size". Biology Letters. 14 (5): 20180135. doi: 10.1098/rsbl.2018.0135 . PMC   6012691 . PMID   29769301.
  12. ↑ Bonde, Varricchio and Jackson, Loope, Shirk, Joshua W., Frankie D. and David J., David B., and Aubrey M. (January 2008). "Dinosaurs and dunes! Sedimentology and paleontology of the Mesozoic in the Valley of Fire State Park". GSA Field Guide 11: Field Guide to Plutons, Volcanoes, Faults, Reefs, Dinosaurs, and Possible Glaciation in Selected Areas of Arizona, California, and Nevada. Vol. 11. pp. 249–262. doi:10.1130/2008.fld011(11). ISBN   978-0-8137-0011-3.{{cite book}}: CS1 maint: multiple names: authors list (link)
  13. ↑ X. Jin, Y. Azuma, F. D. Jackson and D. J. Varricchio. (2007) "Giant dinosaur eggs from the Tiantai basin, Zhejiang province, China." Canadian Journal of Earth Sciences 44:81-88.
  14. ↑ Wang Qiang, Zhao Zikui, Wang Xiaolin, Jiang Yangen, and Zhang Shukang. (2010) "A New Oogenus Of Macroelongatoolithid Eggs From The Upper Cretaceous Chichengshan Formation Of The Tiantai Basin, Zhejiang Province And A Revision Of The Macroelongatoolithids" Acta Paleontologica Sinica 49(1)：73-86.
  15. ↑ Li, G., Chen, P., Wang, D., & Batten, D. J. (2009). "The spinicaudatan Tylestheria and biostratigraphic significance for the age of dinosaur eggs in the Upper Cretaceous Majiacun Formation, Xixia Basin, Henan Province, China." Cretaceous Research, 30(2): 477-482.
  16. ↑ Kim, J. Y., Yang, S. Y., Choi, H. I., Seo, S. J., & Kim, K. S. (2011). Dinosaur eggs from the Cretaceous Goseong formation of Tongyeong City, southern coast of Korea. Journal of the Paleontological Society of Korea 27(1): 13-26.
  17. ↑ Huh, M., Kim, B. S., Woo, Y., Simon, D. J., Paik, I. S., & Kim, H. J. (2014). First record of a complete giant theropod egg clutch from Upper Cretaceous deposits, South Korea. Historical Biology, 26(2), 218–228. https://doi.org/10.1080/08912963.2014.894998
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