This Article Is Essentially a Hoax for April 1 of 2014 For

Home , Aetiocetidae

NOTE: THIS ARTICLE IS ESSENTIALLY A HOAX FOR APRIL 1 OF 2014 FOR

ASHORO MUSEUM OF PALEONTOLOGY, BUT AIMS TO BE A

THOUGHT-PROVOKING PIECE OF WORK TO CONSIDER THE BODY SIZE

EVOLUTION IN MYSTICETI (BALEEN WHALES).

A Lilliputian whale, Aetiocetus hobbitus

Tsai, Cheng-Hsiu

Department of Geology, University of Otago, Dunedin, New Zealand

Whales (Cetacea: Mysticeti) are the largest animals in the world. As the real

Brobdingnagians, how small a whale could be renders an interesting and unresolved

biological question. Here I report a smallest whale “produced” at the Ashoro Museum

of Paleontology (AMP), Hokkaido, Japan.

SYSTEMATIC PALAEONTOLOGY

Cetacea Brisson, 1762

Mysticeti Gray, 1864

Aetiocetidae Emlong, 1966

Aetiocetus Emlong, 1966

Aetiocetus hobbitus sp. nov.

(FIG. 1)

Holotype: AMP0401, including a well-preserved skull and left mandible. Diagnosis: The morphology of AMP0401 is “exactly” the same as Aetiocetus

polydentatus, but the size is considerably smaller. The skull length is about 15 cm.

Etymology: The species epithet, hobbitus, is latinised from The Hobbit written by J.

R. R. Tolkien, describing a fictional, diminutive human species.

Aetiocetus hobbitus represents the smallest mysticete species described and named to date. Body size evolution in baleen whales is particularly tantalising and intriguing,

since baleen whales are the largest animals to have ever lived on Earth. Given the

body size of the earliest known mysticete, Llanocetus denticrenatus, the body size has evolved to both directions in Mysticeti, gigantism: Balaenoptera musculus (blue

whale) and dwarfism: Aetiocetus hobbitus sp. nov. (this study). Understanding the

underlying evolutionary process that influences the body size evolution in baleen

whales in at least two different directions should help decipher the mystery of

mysteries – from Lilliputian to Brobdingnagian in baleen whale evolution.

Acknowledgements: I thank Hiroshi Sawamura, Tatsuro Ando, and Tatsuya

Shinmura for producing and providing this specimen; Yoshihiro Tanaka for helping

the research trip in Hokkaido. University of Otago Doctoral Scholarship supports this study.

Figure 1. The skull of the holotype of Aetiocetus hobbitus sp. nov. AMP0401. A, dorsal view. B, lateral view.