Thylacine	42	147
Quagga	34	18
Baiji	40	116

##</code><code>##

Name       : Thylacine
Latitude   : 42
Longitude  : 147

Name       : Quagga
Latitude   : 34
Longitude  : 18

Name       : Baiji
Latitude   : 40
Longitude  : 116

##</code><code>##

# Always start your scripts with strict and warnings.
use strict;
use warnings;

# With "use strict" you must declare all variables before use
# (this catches errors when you misspell a variable name, for example).
# So we put a "my" in front of @speciesList and others below to declare
# them as lexical variables, which have a scope from the point of
# declaration to end of scope (i.e. end of block or end of file).
my @speciesList = qw(Name Latitude Longitude);

# Put "Mammal.txt" into a variable to avoid having to repeat it.
my $infile = "Mammal.txt";

# BTW, instead of hard-wiring $infile to "Mammal.txt" above
# you could now accept it as a command line argument like so:
# my $infile = shift or die "usage: $0 filename\n";

# Use three-argument open and a lexical file handle.
# Also check if the open fails and die with a useful message if so.
open my $MAMMALS, "<", $infile or die "error: open '$infile': $!";

# Use explicit lexical variables rather than $_
while (my $line = <$MAMMALS>) {
    my %data;
    @data{@speciesList} = split /\t/, $line, scalar @speciesList;
    foreach my $species (@speciesList) {
        printf "%-10.10s : %s\n", $species, $data{$species};
    }
}
close $MAMMALS;

##</code><code>##

# This is a species file
Thylacine   Lat=42   Long=147
Quagga      Lat=34   Long=18
Baiji       Lat=40   Long=116