The February 28, 1957 Lowell Sun (Lowell, MA) ran a fantastic piece about the plant and animal life we would likely find on Mars. A map that accompanied the piece even laid out where the likely vegetation, deserts, canals and oases were located.
The 1957 Disneyland TV episode Mars and Beyond shared many of the same assumptions about animal life on the Red Planet. Of course it would be difficult for life to sustain itself on Mars, that's why they're Martians!
An excerpt from the Lowell Sun piece appears below.
The Martians greeting the first space travelers from Earth may be fantastic furry little creatures peeking out of lonesome burrows.
Speculation that Mars might have animal life is contained in a book, "A Space Traveler's Guide to Mars," by Dr. I. M. Levitt of the Fels Planetarium, Philadelphia.
But these Martians would be astonishingly different from earthly animals, living by a different chemistry of life dictated by severe conditions of our Red Planet neighbor.
Many astronomers think Mars has some kind of plant life. One bit of evidence is changes in blue-green areas, which could be plant life spreading with the seasons over the Martian deserts.
And if there are plants, are there animals that feed on them and help decompose dead plants?
Animal Life on Mars (1957)
Plant Life on Mars (1957)
Mars and Beyond (1957)