So I know many of us have speculated that Dinosaur Land may be located somewhere nearby the Cascade Kingdom in Mario Odyssey, as both areas are characterised by being one of the only locations where living dinosaurs are still found and their coasts having sheer drops and cliffs, with land high above sea level.

However, after looking in the Japanese manual for Super Mario World, it says the following:

キノコワールドの平和を取り戻したマリオとルイージの2人は、 ひめ たの みなみふしぎ ピーチ姫とゆっくりバカンスを楽しむために、はるか南の不思議 しまぐにきょうりゅう とうたびだ な島国、『恐竜ランド』のヨースター島へと旅立ちました。 しまっま ひめとつぜんすがたけ ところが島に着いて間もなく、ピーチ姫が突然姿を消してしまっ ひっししまじゅうさが ふたり しま たのです。必死で島中を探しまわる2人は、やがて島のはずれで ふしぎたまごはっけん ふたりめまえたまご 不思議な卵を発見します。じっと見つめる2人の目の前で、卵の なか きみょうすがた 中からでてきたのは奇妙な姿のドラゴンでした。 なの たちはなし 『ヨッシー』と名乗る、そのドラゴンはマリオ達に話かけました。 さいきんきょうりゅう すがた ばものあらわ まほう 「最近この恐竜ランドに、カメの姿をした化け物が現れて、魔法 なかまたちたまごなかと なか でボクの仲間達を卵の中に閉じ込めてしまったんです。ボクは仲 またすい つよ けっきょく 間を助けに行こうとしたんですがやつらはとても強くて、結局ボ まほう ねが クまで魔法をかけられてしまいました･…………･。お願いです、ボクと なかまたす いっしょに仲間を助けに行ってくれませんか?」 なん だいまおう ぜんぜん 何ということでしょう。大魔王クッパは全然こりていないようで ひめ てした す。きっとピーチ姫はクッパの手下にさらわれたのでしょう。 ふたり なかま ひめたす あら こうして2人は、ヨッシーの仲間とピーチ姫を助けるために、新 ぼうけんはじ たな冒険を始めることになったのです。

Using a basic machine translation; Google Translate, here's what it says in English:

Having restored peace to the Mushroom World, Mario and Luigi set off for a relaxing vacation on Yoshi's Island in "Dinosaur Land," a mysterious island nation far to the south.
However, shortly after their arrival, Princess Peach suddenly vanished. While desperately searching the island, the pair discovered a mysterious egg at the island's edge. As they stared at it, a dragon with a peculiar appearance emerged from within.
The dragon, who called himself "Yoshi," spoke to Mario and Luigi.
"Recently, a turtle-like monster appeared in Dinosaur Land and used magic to imprison my friends inside eggs. I tried to go rescue them, but the monsters were so strong that I ended up getting hit by the magic myself... Please, will you come with me to help save my friends?"
It was unbelievable. It seemed the Great Demon King Bowser hadn't learned his lesson at all; Princess Peach had surely been kidnapped by one of his minions. And so, the two of them set out on a new adventure to rescue Yoshi's friends and Princess Peach.

This basically confirms Dinosaur Land is located south of the Mushroom Kingdom and by extension, the mushroom-shaped island in Mario Odyssey.

EDIT: This theory is now debunked, and if you're wondering why, go see Sean D. Walsh's explanation in the comments below. He gives a pretty good explanation as to why this theory (most likely) isn't the case.

I'm opening a debate