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Yoshikazu Hasegawa

Science / Paleontology

Yoshikazu Hasegawa

1930 – 2026 · aged 96 · Vertebrate paleontologist; university professor; museum director

He showed Japan its first plesiosaur and spent a life reading fossil bones.

Portrait: Yomiuri Shimbun

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103 people are remembering Yoshikazu here

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Yoshikazu Hasegawa (長谷川 善和) was a Japanese vertebrate paleontologist, university professor, and museum director. He was born on 12 March 1930 in Chiyo, then a village in Shimoina District, Nagano Prefecture, now part of Iida City. The Iida City Art Museum, where he later served as an adviser, recorded that…

Biography adapted from Kyodo via Kumamoto Nichinichi and Sankei Sports; Yomiuri; Shinano Mainichi; Iida City Art Museum; YNU Proud Alumni CV; Wikipedia (EN/JA); Mammal Society of Japan..

In their own words

Paleoparadoxia was an animal he knew well. He had cleaned Toki City fossils as a student and supervised the pose of a replica at the Mizunami Fossil Museum. The new specimen had bones connected from head to tail and teeth in place. The skull was almost uncrushed. He thought it the best preserved Paleoparadoxia yet found in Japan, and he looked forward to the reconstructed skeleton as research and display material for Mizunami.

English rendering of Yoshikazu Hasegawa's published comment on the Furusato Choice page for the Mizunami Paleoparadoxia full-skeleton restoration (project 1830). He is identified there as Yokohama National University emeritus professor and Gunma Museum of Natural History honorary director. Not a wor

At their first meeting the teacher in a beret looked radiant. He wrote many books. I respected him. I am truly sorry.

Tadashi Suzuki, 75, the Iwaki man who found the bones as a high-school student, to the Yomiuri Shimbun, 2026-09-05. English rendering paraphrased from the Yomiuri Fukushima report, not a verbatim transcript.

Photos

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Yoshikazu Hasegawa, the Japanese vertebrate paleontologist, in the Yomiuri Shimbun portrait published with the 4 September 2026 obituary.
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Videos

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Mizunami City official: Paleoparadoxia cleaning, special edition, cited as footage from Hasegawa's visit.
1d ago

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Greeting by Yoshikazu Hasegawa at the 2012 Dinosaur Kingdom press event (channel mononychus).
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Gunma Prefecture official: full 25th-anniversary dialogue between honorary director Yoshikazu Hasegawa and special director Makoto Manabe (upload 2022-03-08).
1d ago

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Tributes

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Memories, thanks and farewells from the people Yoshikazu touched.

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A man who swung his own hammer and built something real.

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Never heard of him before today but the plesiosaur discovery is genuinely cool. RIP to a real pioneer.

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He opened doors to Japan's deep past. A life well spent reading what the stones had to say.

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Saw a documentary once about his team digging up that ancient marine reptile. Careful work. Patient man.

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What strikes me most is how he never put up walls between himself and people asking questions. He answered them all carefully, even the amateurs. That's the kind of scholar we need more of. Rest well, Hasegawa sensei.

Michelle Palmer3d ago

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That's a beautiful way to remember him. He made science belong to everyone.

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I never met him but my son brought home a book about Japanese plesiosaurs when he was ten, and it changed everything for that kid. Hasegawa's name was on it. A life spent teaching people to see what's written in bone. That matters.

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96 years and he was still walking the slopes. Still thinking about bones. That's a life.

Candles

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103 people are remembering Yoshikazu here. Light a candle when words are hard. It stays here.

Emilio Garcia🇪🇸1d ago
Danielle Oakley🇺🇸1d ago
Long life, bright mind, open door. Hasegawa sensei was all three.
Helmut Lang🇺🇸1d ago
Ninety-six years old and still the most vital man in the room. Rest now, sensei.
Katie Ross🇺🇸1d ago
Ernest Lattimore🇺🇸1d ago
The man who showed Japan its first sea dragon. Rest well, teacher.
Henry Marshall🇺🇸1d ago
Futaba to Gunma. The museums he opened still hold the bones he loved.
Patrick Lewis🇬🇧1d ago
A life spent reading the earth. We are all richer for what he found.
Crystal Suggs🇺🇸1d ago
Rafael Castro🇺🇸1d ago
A scientist who answered amateurs as carefully as colleagues. That speaks volumes.
Steven Blake🇺🇸2d ago
Diane Barnes🇨🇦2d ago
The first plesiosaur changed how Japan saw itself. That was his gift.
Shirley James🇨🇦2d ago
Archie Harrison🇺🇸2d ago
Mai Song🇦🇺2d ago
Latasha Williams🇺🇸2d ago
Shira Hoffman🇺🇸2d ago
Tyrone Kirby🇺🇸2d ago
Iida born. Tokyo trained. Japan changed. That is his story.
Lachlan Lowe🇺🇸2d ago
Elaine Cannon🇺🇸2d ago
Janet Harrison🇺🇸2d ago
Answered amateurs carefully, dug with his own hammer, kept no wall. A good scholar.
Showing 20 of 95

A boy from Chiyo, Iida

Born 1930-03-12 in Chiyo, Shimoina District, Nagano Prefecture, now Chiyo, Iida City. The Iida City Art Museum memorial and Yokohama National University's proud-alumni CV both place that birth in Iida country. He finished Iida Takamatsu High School. No public biography consulted names his parents. Japanese press and students later called him 長谷川先生. Sources: Iida City Art Museum memorial, 2026-09; Japanese Wikipedia; YNU Proud Alumni CV.

Yokohama, then a Tokyo doctorate on elephants

In 1955 he graduated from the Faculty of Liberal Arts at Yokohama National University, entered the geology graduate course, and from November became an assistant. In 1972 he earned a Doctor of Science from the University of Tokyo for a study of the Naumann's elephant, Palaeoloxodon naumanni, from late Pleistocene deposits off Shakagahana, Shodoshima, in the Seto Inland Sea. The…

From the Futaba bones to a museum he opened

In 1965 he joined the National Science Museum in Tokyo as a technical official of the education ministry, continuing as a Yokohama National University part-time lecturer. He became a museum researcher in 1969 and a senior researcher in 1975. In 1968 high-school student Tadashi Suzuki found bones in Iwaki, Fukushima. Hasegawa judged them a plesiosaur. A first survey that year…

A Kanagawa home and a son named Shinichi

Obituaries do not name a spouse or parents. They name his eldest son Shinichi (真一; also written Shin'ichi) as chief mourner. Other children are not named. Home at death: Kanagawa Prefecture. The city of the house is not named beyond the prefecture. The funeral and farewell service were set for 10:30 a.m. on 8 September 2026 at Kamakura Family Hall,…

Careful bones, open doors

Documented habits, not a political manifesto. Colleagues in Iwaki remembered a scientist who swung the hammer himself, answered amateurs carefully, and had no wall around him. Satoshi Nabana, honorary curator at the Iwaki City Coal and Fossil Museum, told the Yomiuri that Hasegawa was full of vitality and dug with his own hammer, and that about ten years earlier he…

The find that made Japan look for dinosaurs

Futabasaurus suzukii, formally named in 2006, was the first elasmosaurid from Japan and, in the Japanese press, the spark for later dinosaur hunts. The Yomiuri wrote that the work overturned the idea that dinosaur-age marine reptiles of this kind were not found in Japan. He also identified Moshiryu and Mifuneryu, helped found or shape several natural-history museums, supervised mass-market dinosaur…

Nice Step, a MEXT prize, and the mammal society's honours

In 2007 he was named among the "Nice Step" researchers for a notable contribution to science and technology, and he shared that year's MEXT Prize for Public Understanding of Science and Technology with Tamaki Sato for work on Futabasaurus. The Mammal Society of Japan awarded him its prize in 2011 (its fourth such prize) and a special prize in 2012,…

None documented in obituaries

No scandal, resignation fight, or misconduct claim appears in the Kyodo, Yomiuri, Shinano Mainichi, or museum memorials consulted. Scientific naming took time: the informal "Futaba Suzuki dragon" waited until 2006 for a formal genus and species. That delay is described as careful work, not controversy. Sources: Yomiuri; YNU.

Home in Kanagawa, 2 September 2026

Died 2026-09-02 at 7:54 a.m. at home in Kanagawa Prefecture, age 96, of pancreatic cancer (膵がん). Kyodo, the Yomiuri, the Shinano Mainichi, and Sankei Sports agree on the date, time, place, age, and cause. The city of the house is not named beyond Kanagawa. Research on mammal fossils continued until just before death, per Kyodo and Sankei Sports. Yoshitsugu Kobayashi wrote that morning that the news had just reached him, that he and Manabe had visited at the start of the previous month, and that a summer Mongolia trip the three had planned would go on without Hasegawa.

The funeral and farewell service were set for 10:30 a.m. on 8 September 2026 at Kamakura Family Hall, 2-17-15 Ofuna, Kamakura. Chief mourner: eldest son Shinichi. Burial place after that service is not made public. The Iida City Art Museum asked the public not to send condolence money, flowers, or offerings there. The YNU proud page also records 享年97. Age at death used here is 96. Sources: Kyodo; Yomiuri; Sankei Sports; Iida City Art Museum.

Questions people ask about Yoshikazu

Who was Yoshikazu Hasegawa?
A Japanese vertebrate paleontologist (1930-2026), emeritus professor at Yokohama National University and honorary director of the Gunma Museum of Natural History, known for the Futaba plesiosaur and for Japanese mammal fossils. His Japanese name is 長谷川 善和.
What was Yoshikazu Hasegawa known for?
Leading the study of the Iwaki plesiosaur later named Futabasaurus suzukii, and for a long career on Japanese vertebrate fossils and natural-history museums.
When did Yoshikazu Hasegawa die?
2026-09-02, at 7:54 a.m., according to Kyodo and the Yomiuri. He died at home in Kanagawa Prefecture.
How did Yoshikazu Hasegawa die?
Pancreatic cancer (膵がん), at home. Kyodo and the Yomiuri reported the cause. It was not withheld.
How old was Yoshikazu Hasegawa when he died?
96. The YNU proud page also prints 享年97, the traditional Japanese count. Do not treat 97 as the Western age.
Where was Yoshikazu Hasegawa born?
Chiyo, Shimoina District, Nagano Prefecture (now Chiyo, Iida City), on 1930-03-12.
Where did Yoshikazu Hasegawa die?
At home in Kanagawa Prefecture. The city of the house is not named in the wire obituaries. The funeral was set for Kamakura.
What is Futabasaurus?
An elasmosaurid plesiosaur from the Late Cretaceous Futaba Group of Fukushima, formally named Futabasaurus suzukii in 2006 by Tamaki Sato, Yoshikazu Hasegawa, and Makoto Manabe. The nickname Futabasuzukiryu honours the Futaba rocks and discoverer Tadashi Suzuki.
Did Yoshikazu Hasegawa discover the Iwaki fossil himself?
Suzuki, then a high-school student, found the bones. Hasegawa, then at the National Science Museum, judged them to be a plesiosaur and led the 1968 and 1970 excavations and the later scientific work.
Was Yoshikazu Hasegawa married?
Obituaries consulted do not name a spouse. They name eldest son Shinichi as chief mourner. Spouse's name: not made public.
Did Yoshikazu Hasegawa have children?
Yes. Eldest son Shinichi (真一), chief mourner. Other children are not named in the obituaries consulted.
What museum did Yoshikazu Hasegawa direct?
He was the first director of the Gunma Museum of Natural History in Tomioka from its 1996 opening, later honorary director. Yomiuri dates the honorary-director role from 2010. He was still honorary director at his death.
Where is Yoshikazu Hasegawa buried?
Not made public beyond the 2026-09-08 funeral and farewell service at Kamakura Family Hall, Ofuna, Kamakura.
How do you pronounce Yoshikazu Hasegawa?
yoh-shee-KAH-zoo hah-seh-GAH-wah. Japanese reading: はせがわ よしかず.

Written by People Forever from Wikipedia (CC BY-SA 4.0) and the reporting cited. Updated . Spotted a mistake? Tell us.

From social media

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Posts by Yoshikazu, and posts about them, kept here so they are not lost.

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Timeline

  1. 12 March 1930
    Born in Chiyo, Shimoina District, Nagano Prefecture, Japan (now Chiyo, Iida City)
  2. 12 March 1930
    Born in Chiyo, Nagano

    Born in Chiyo, Shimoina District, Nagano Prefecture (now Chiyo, Iida City).

  3. 1 January 1955
    Graduates Yokohama National University; assistant from November

    Graduated Yokohama National University Faculty of Liberal Arts; entered the geology graduate course; assistant from November. Year-only date. May persist as 1955-01-01. November start kept in this description.

  4. 1 January 1957
    Describes the fossil insectivore Shikamainosorex

    Described the fossil insectivore Shikamainosorex. Year-only date. May persist as 1957-01-01.

  5. 1 January 1964
    Part-time lecturer at Yokohama National University

    Part-time lecturer, Yokohama National University. Year-only date. May persist as 1964-01-01.

  6. 1 January 1965
    Technical official, National Science Museum

    Technical official, National Science Museum; continued as YNU part-time lecturer. Year-only date. May persist as 1965-01-01.

  7. 1 January 1968
    First Futabasaurus survey, Iwaki

    First Futabasaurus survey, Iwaki, based on Tadashi Suzuki's find. Year-only date. May persist as 1968-01-01.

  8. 1 January 1969
    Researcher, National Science Museum

    Researcher, National Science Museum. Year-only date. May persist as 1969-01-01.

  9. 1 January 1970
    Second Futabasaurus excavation

    Second Futabasaurus excavation. Year-only date. May persist as 1970-01-01.

  10. 1 January 1972
    Doctor of Science, University of Tokyo

    D.Sc., University of Tokyo, on Palaeoloxodon naumanni from off Shakagahana, Shodoshima. Year-only date. May persist as 1972-01-01.

  11. 1 January 1973
    Academic fieldwork in Madagascar

    Academic fieldwork in Madagascar. A second Madagascar survey followed in 1975 (kept on the 1975 entry, not skipped). Year-only date. May persist as 1973-01-01.

  12. 1 January 1975
    Senior researcher; second Madagascar survey

    Senior researcher, National Science Museum geology department; part-time lecturer, University of the Ryukyus. Second Madagascar survey, from the 1973 vitae note. Year-only date. May persist as 1975-01-01.

  13. 1 January 1976
    Ethiopia survey; Speleological Society councillor

    Councillor, Speleological Society of Japan (until 1993); Ethiopia survey. The 1976-1993 range is kept in this description. Year-only date. May persist as 1976-01-01.

  14. 1 August 1978
    Identifies the Iwate Moshiryu fossil

    Identified the Iwate Moshiryu fossil in August 1978. Stored as 1978-08. Exact day not published. API may persist as 1978-08-01.

  15. 1 January 1979
    Professor, Yokohama National University

    Professor, Faculty of Education, Yokohama National University. Year-only date. May persist as 1979-01-01.

  16. 1 January 1980
    Introduces Moshiryu at Iwate Prefectural Museum

    Lecture at Iwate Prefectural Museum opening, introducing Moshiryu. Year-only date. May persist as 1980-01-01.

  17. 1 January 1981
    Compares Mamenchisaurus and Moshiryu bones

    Compared Mamenchisaurus and Moshiryu bones for the "Dinosaurs of China" exhibition. Year-only date. May persist as 1981-01-01.

  18. 1 January 1984
    Identifies the Kumamoto Mifune meat-eating dinosaur fossil

    Identified the Kumamoto Mifune fossil as Japan's first meat-eating dinosaur specimen. Year-only date. May persist as 1984-01-01.

  19. 1 January 1988
    Nihon no kyoryu published; Iida museum adviser

    Children's book Nihon no kyoryu published. Became adviser to Iida City Art Museum. Year-only date. May persist as 1988-01-01.

  20. 1 January 1991
    Moshiryu paper treated as Japan's first dinosaur paper

    Paper treating Moshiryu as Japan's first dinosaur published. Year-only date. May persist as 1991-01-01.

  21. 1 January 1995
    Retires from YNU; adviser, Gunma Museum

    Retired from Yokohama National University. Adviser, Gunma Museum of Natural History. Year-only date. May persist as 1995-01-01.

  22. 1 January 1996
    First director, Gunma Museum of Natural History

    First director, Gunma Museum of Natural History, Tomioka, at opening. Year-only date. May persist as 1996-01-01.

  23. 1 January 1998
    Chairs the Mammal Society meeting in Tomioka

    Chaired the Mammal Society of Japan meeting in Tomioka, the first to pass 350 participants. The same year his book Kyoryu hakkutsu-ki was published. Year-only date. May persist as 1998-01-01.

  24. 1 January 2006
    Co-author of Futabasaurus suzukii

    Co-author of the formal description of Futabasaurus suzukii in Palaeontology, with Tamaki Sato and Makoto Manabe. Year-only date. May persist as 2006-01-01.

  25. 1 January 2007
    Nice Step list and MEXT public-understanding prize

    Nice Step researchers list; MEXT Prize for Public Understanding of Science and Technology, shared with Tamaki Sato. Year-only date. May persist as 2007-01-01.

  26. 1 January 2008
    Futaba excavation book published

    Book Futabasukikiryu hakkutsu monogatari published. Year-only date. May persist as 2008-01-01.

  27. 1 January 2010
    Honorary director, continuing lectures

    Yomiuri: began as honorary director and continued lectures. Year-only date. May persist as 2010-01-01.

  28. 1 January 2011
    Mammal Society of Japan Prize

    Mammal Society of Japan Prize. Year-only date. May persist as 2011-01-01.

  29. 1 January 2012
    Mammal Society of Japan Special Prize

    Mammal Society of Japan Special Prize. Still honorary director on the YNU vitae. Year-only date. May persist as 2012-01-01.

  30. 1 January 2015
    Shiriyanetta hasegawai named for him

    Shiriyanetta hasegawai named in the Journal of Vertebrate Paleontology. Year-only date. May persist as 2015-01-01.

  31. 1 January 2018
    Named a YNU Proud Alumnus

    Named a Yokohama National University Proud Alumnus. Year-only date. May persist as 2018-01-01.

  32. 8 March 2022
    Gunma posts the 25th-anniversary dialogue

    Gunma Prefecture posted the full 25th-anniversary dialogue between honorary director Hasegawa and special director Makoto Manabe.

  33. 1 August 2026
    Kobayashi and Manabe visit at the start of August

    Kobayashi wrote that he and Manabe had visited Hasegawa at the start of this month. Exact day not published. Stored as 2026-08. API may persist as 2026-08-01.

  34. 2 September 2026
    Dies at home in Kanagawa, age 96

    Died 7:54 a.m. at home in Kanagawa, age 96, pancreatic cancer. The same day Yoshitsugu Kobayashi's X tribute was posted at 13:07 UTC (22:07 Japan time) via @dino_mamire. Original death date is 2026-09-02, not a later notice date.

  35. 2 September 2026
    Died in At home in Kanagawa Prefecture, Japan
  36. 4 September 2026
    Kyodo and Yomiuri obituaries published

    Kyodo and Yomiuri obituaries published. Kobayashi's X tribute itself is dated 2026-09-02 and is kept on that day's entry, not moved here.

  37. 8 September 2026
    Funeral and farewell service, Kamakura Family Hall

    Funeral and farewell service set for 10:30 a.m., Kamakura Family Hall, Ofuna. Chief mourner: eldest son Shinichi. Burial place after the service not made public.

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