Acreodi

Acreodi; Temporal range: ; Early Paleocene—Late Eocene, 65.4–34 Ma PreꞒ Ꞓ O S D C P T J K Pg N Suspected Late Cretaceous origins
	Various Acreodi genera from Nacimiento Formation. From top: Ankalagon, Dissacus, and Triisodon
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Clade:	Scrotifera
Grandorder:	Ferungulata
Clade:	Pan-Euungulata
Order:	†Acreodi; Matthew, 1909
Subgroups
	†Andrewsarchus; †Mesonychia; †Mondegodon; †Triisodontidae; †Olseniidae;
Synonyms
	Mesonychia (Rose, 2006);

Acreodi is an informal order of ungulate-like mammals that lived during the Paleogene, first appearing in the Early Paleocene, before going extinct during the Late Eocene. The earliest Acreodi appeared roughly 600,000 years after the extinction of the non-avian dinosaurs. The order consisted of groups such as Triisodontidae, Mesonychia, Olseniidae, as well as Andrewsarchus and Mondegodon.

Originally, Acreodi were thought to have been ancestral or closely related to Cetacea. However, more recent analysis found Cetacea to be nested within Artiodactyla. The order is also now thought to have been a polyphyletic group of unrelated mammals with Andrewsarchus being recovered within Cetancodontamorpha. Triisodontids have been recovered as being more closely related to ungulates than to mesonychians.

References

↑ Solé, Floréal; Fournier, Morgane; Ladevèze, Sandrine; et al. (2023). "New postcranial elements of mesonychid mammals from the Ypresian of France: New hypotheses for the radiation and evolution of the mesonychids in Europe". Journal of Mammalian Evolution. 30 (2): 371–401. doi:10.1007/s10914-023-09651-x.
↑ Gingerich, Philip D.; Uhen, Mark D. (1998). "Likelihood estimation of the time of origin of Cetacea and the time of divergence of Cetacea and Artiodactyla". Palaeontologia Electronica. doi:10.26879/98008.
1 2 Kondrashov, Peter E.; Lucas, Spencer G. (2002). Sullivan, Robert M.; Lucas, Spencer G. (eds.). EARLY PALEOCENE (PUERCAN AND TORREJONIAN) ARCHAIC UNGULATES (CONDYLARTHRA, PROCREODI AND ACREODI) OF THE SAN JUAN BASIN, NEW MEXICO. New Mexico Museum of Natural History and Science.
↑ Tsubamoto, Takehisa, et al. "Fossil evidence of a mesonychid mammal from the upper Eocene Ergilin Dzo Formation, Mongolia." Paleontological Research 16.2 (2012): 171-174.
↑ T. R. Lyson; I. M. Miller; A. D. Bercovici; K. Weissenburger; A. J. Fuentes; W. C. Clyde; J. W. Hagadorn; M. J. Butrim; K. R. Johnson; R. F. Fleming; R. S. Barclay; S. A. Maccracken; B. Lloyd; G. P. Wilson; D. W. Krause; S. G. B. Chester (October 2019). "Exceptional continental record of biotic recovery after the Cretaceous–Paleogene mass extinction". Science. 366 (6468): 977–983. doi:10.1126/science.aay2268. PMID 31649141. S2CID 204883579.
↑ Erfurt, Jörg; Averianov, Alexander (2006). "Enigmatic ungulate-like mammals from the Eocene of Central Asia". Naturwissenschaften. 92: 182–187.
1 2 Rodolphe Tabuce, Julien Clavel and Miguel Telles Antunes (2011). "A structural intermediate between triisodontids and mesonychians (Mammalia, Acreodi) from the earliest Eocene of Portugal". Naturwissenschaften. 98 (2): 145–155. Bibcode:2011NW.....98..145T. doi:10.1007/s00114-010-0747-y. PMID 21181109. S2CID 22526630.
1 2 Spaulding, Michelle; O'Leary, Maureen A.; Gatesy, John (2009-09-23). "Relationships of Cetacea (Artiodactyla) Among Mammals: Increased Taxon Sampling Alters Interpretations of Key Fossils and Character Evolution". PLOS ONE. 4 (9) e7062. Bibcode:2009PLoSO...4.7062S. doi:10.1371/journal.pone.0007062. ISSN 1932-6203. PMC 2740860. PMID 19774069.
↑ Thewissen, J G M; Cooper, Lisa Noelle; Clementz, Mark T.; Bajpai, Sunil. "Whales originated from aquatic artiodactyls in the Eocene Epoch of India". ResearchGate. Archived from the original on 2025-11-15. Retrieved 2026-02-14.
1 2 Yu, Yang; Gao, Hongyan; Li, Qiang; Ni, Xijun (2023-01-01). "A new entelodont (Artiodactyla, Mammalia) from the late Eocene of China and its phylogenetic implications". Journal of Systematic Palaeontology. 21 (1). doi:10.1080/14772019.2023.2189436. ISSN 1477-2019.
↑ Solé, Floréal; Fournier, Morgane; Ladevèze, Sandrine; et al. (2023). "New postcranial elements of mesonychid mammals from the Ypresian of France: New hypotheses for the radiation and evolution of the mesonychids in Europe". Journal of Mammalian Evolution. 30 (2): 371–401. doi:10.1007/s10914-023-09651-x.

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[Solé-2023-1] Solé, Floréal; Fournier, Morgane; Ladevèze, Sandrine; et al. (2023). "New postcranial elements of mesonychid mammals from the Ypresian of France: New hypotheses for the radiation and evolution of the mesonychids in Europe". Journal of Mammalian Evolution. 30 (2): 371–401. doi:10.1007/s10914-023-09651-x.

[2] Gingerich, Philip D.; Uhen, Mark D. (1998). "Likelihood estimation of the time of origin of Cetacea and the time of divergence of Cetacea and Artiodactyla". Palaeontologia Electronica. doi:10.26879/98008.

[:03-3] 1 2 Kondrashov, Peter E.; Lucas, Spencer G. (2002). Sullivan, Robert M.; Lucas, Spencer G. (eds.). EARLY PALEOCENE (PUERCAN AND TORREJONIAN) ARCHAIC UNGULATES (CONDYLARTHRA, PROCREODI AND ACREODI) OF THE SAN JUAN BASIN, NEW MEXICO. New Mexico Museum of Natural History and Science.

[Tsubamoto-4] Tsubamoto, Takehisa, et al. "Fossil evidence of a mesonychid mammal from the upper Eocene Ergilin Dzo Formation, Mongolia." Paleontological Research 16.2 (2012): 171-174.

[:7-5] T. R. Lyson; I. M. Miller; A. D. Bercovici; K. Weissenburger; A. J. Fuentes; W. C. Clyde; J. W. Hagadorn; M. J. Butrim; K. R. Johnson; R. F. Fleming; R. S. Barclay; S. A. Maccracken; B. Lloyd; G. P. Wilson; D. W. Krause; S. G. B. Chester (October 2019). "Exceptional continental record of biotic recovery after the Cretaceous–Paleogene mass extinction". Science. 366 (6468): 977–983. doi:10.1126/science.aay2268. PMID 31649141. S2CID 204883579.

[6] Erfurt, Jörg; Averianov, Alexander (2006). "Enigmatic ungulate-like mammals from the Eocene of Central Asia". Naturwissenschaften. 92: 182–187.

[Mondegodon-7] 1 2 Rodolphe Tabuce, Julien Clavel and Miguel Telles Antunes (2011). "A structural intermediate between triisodontids and mesonychians (Mammalia, Acreodi) from the earliest Eocene of Portugal". Naturwissenschaften. 98 (2): 145–155. Bibcode:2011NW.....98..145T. doi:10.1007/s00114-010-0747-y. PMID 21181109. S2CID 22526630.

[Spaulding-2009-8] 1 2 Spaulding, Michelle; O'Leary, Maureen A.; Gatesy, John (2009-09-23). "Relationships of Cetacea (Artiodactyla) Among Mammals: Increased Taxon Sampling Alters Interpretations of Key Fossils and Character Evolution". PLOS ONE. 4 (9) e7062. Bibcode:2009PLoSO...4.7062S. doi:10.1371/journal.pone.0007062. ISSN 1932-6203. PMC 2740860. PMID 19774069.

[:2-9] Thewissen, J G M; Cooper, Lisa Noelle; Clementz, Mark T.; Bajpai, Sunil. "Whales originated from aquatic artiodactyls in the Eocene Epoch of India". ResearchGate. Archived from the original on 2025-11-15. Retrieved 2026-02-14.

[:1-10] 1 2 Yu, Yang; Gao, Hongyan; Li, Qiang; Ni, Xijun (2023-01-01). "A new entelodont (Artiodactyla, Mammalia) from the late Eocene of China and its phylogenetic implications". Journal of Systematic Palaeontology. 21 (1). doi:10.1080/14772019.2023.2189436. ISSN 1477-2019.

[:0-11] Solé, Floréal; Fournier, Morgane; Ladevèze, Sandrine; et al. (2023). "New postcranial elements of mesonychid mammals from the Ypresian of France: New hypotheses for the radiation and evolution of the mesonychids in Europe". Journal of Mammalian Evolution. 30 (2): 371–401. doi:10.1007/s10914-023-09651-x.