You cannot make an animated line directly from an errorbar, but you can draw the error bar in steps to make it appear animated:
x = 1:10:100;
y = [20 30 45 40 60 65 80 75 95 90];
figure
ax = gca;
axis([0 100 10 110]);
for k = 1:numel(x)
% all values until the current time step
xVals = x(1:k);
yVals = y(1:k);
% error bars will be 5 units below and 10 units above each point
negativeDelta = 5*ones(1,numel(yVals));
positiveDelta = 10*ones(1,numel(yVals));
% draw the error bar
errorbar(ax,x(1:k),y(1:k),negativeDelta,positiveDelta);
% maintain axis limits since errorbar function will dynamically change
% the axis limits
axis([0 100 10 110]);
% pause between time steps to simulate animation
pause(0.5)
end
