YA Science Fiction family marooned on Venus and Oscar the dinosaur?

This was the first science fiction book I ever read at the age of 6 around 1964 (so the book predates that year). I remember a space ship that might have been sabotaged and ended up crash landing on Venus. The family makes do like the Swiss Family Robinson. They discover life forms, one is sort of slow and bovine, some sort of Venusian dinosaur, and I vividly remember them making steaks out of these creatures. One is adopted as a pet and I think they named it Oscar. The Venusian day is months long and they've crashed in daylight. In exploring a cave they run across giant bats that use their hypersonic voices to stun prey. When the months long Venusian night comes the giant bats will come out and they will all be doomed. Except they're rescued at the last minute! (Whew. Thanks for YA endings!).

I'm aware my memory can be really faulty about details since this is almost 50 years ago. I'm a reference liberrian and used to helping people with similar questions. I also have access to lots of killer tools and databases but I've never been able to find out what I read. My Achilles heel. My Kryptonite. My poor, lost, first science fiction read!

Help me, Obi Wan Kenobi! You're my only hope!

WorldCat.org search results, see if you recognise anything.

One of those results is this. Summary from books.google.com.

Lost on Venus : the thrilling story of two boys who land on the planet and explore a fantastic world.
Mary Elwyn Patchett - 1954 - 192 pages
Two young space trainees are chosen to take a test flight over Venus, but their rocket crashes and they encounter dangerous alien wildlife in their struggle to survive until they are rescued.

London : Lutterworth Press, 1954.
Subjects: Life on other planets -- Juvenile fiction.
Wilderness survival -- Outer space -- Juvenile fiction.
Science fiction.
Extraterrestrial beings -- Juvenile fiction.
Venus (Planet) -- Juvenile fiction.
Outer space -- Exploration -- Juvenile fiction.

Philip Latham's Five against Venus it is! Thanks, bookel! You've also taught this old hand a new technique on WorldCat for similar searches (something I should have known, but didn't). Proof that old dogs (me) can learn new tricks.

Latham's novel is fairly inexpensive so I'm off to AbeBooks! Tally ho!

Ah yes, looked at that one but couldn't find a plot, glad you found it!

And just for the record (and closure), the Venusian "saurian" adopted as a pet was named Oswald, and not Oscar (hey, this was half a century ago, give me a break). I did get a copy with dust jacket from AbeBooks and it is now one of my most cherished tomes.

Thanks again bookel! Good job!

You're the one who recognised it. :) Glad you found a nice copy!